\input texinfo @c -*-texinfo-*- @c @c Please convert this manual with `texi2dvi -e groff.texinfo' due to @c problems in texinfo regarding expansion of user-defined macros. @c @c You need texinfo 4.6 or newer to format this document! @c @c %**start of header (This is for running Texinfo on a region.) @setfilename groff @settitle The GNU Troff Manual @setchapternewpage odd @footnotestyle separate @c %**end of header (This is for running Texinfo on a region.) @smallbook @finalout @copying This manual documents GNU @code{troff} version 1.19. Copyright @copyright{} 1994-2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. @quotation Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover texts being `A GNU Manual,'' and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled `GNU Free Documentation License.'' (a) The FSF's Back-Cover Text is: `You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.'' @end quotation @end copying @c We use the following indices: @c @c cindex: concepts @c rqindex: requests @c esindex: escapes @c vindex: registers @c kindex: commands in font files @c pindex: programs and files @c tindex: environment variables @c maindex: macros @c stindex: strings @c opindex: operators @c @c tindex and cindex are merged. @defcodeindex rq @defcodeindex es @defcodeindex ma @defcodeindex st @defcodeindex op @syncodeindex tp cp @c To avoid uppercasing in @deffn while converting to info, we define @c our special @Var{}. @c @c Due to a (not officially documented) `feature' in makeinfo 4.0, @c macros are not expanded in @deffn (but the macro definition is @c properly removed), so we have to define @Var{} directly in TeX also. @macro Var{arg} \arg\ @end macro @tex \gdef\Var#1{\var{#1}} @end tex @c To assure correct HTML translation, some ugly hacks are necessary. @c While processing a @def... request, the HTML translator looks at the @c next line to decide whether it should start indentation or not. If @c it is something starting with @def... (e.g. @deffnx), it doesn't. @c So we must assure during macro expansion that a @def... is seen. @c @c The following macros have to be used: @c @c One item: @c @c @Def... @c @c Two items: @c @c @Def...List @c @Def...ListEnd @c @c More than two: @c @c @Def...List @c @Def...Item @c @Def...Item @c ... @c @Def...ListEnd @c @c The definition block must end with @c @c @endDef... @c @c The above is valid for texinfo 4.0f and above. @c a dummy macro to assure the `@def...' @macro defdummy @end macro @c definition of requests @macro Defreq{name, arg} @deffn Request @t{.\name\} \arg\ @rqindex \name\ @end macro @macro DefreqList{name, arg} @deffn Request @t{.\name\} \arg\ @defdummy @rqindex \name\ @end macro @macro DefreqItem{name, arg} @deffnx Request @t{.\name\} \arg\ @defdummy @rqindex \name\ @end macro @macro DefreqListEnd{name, arg} @deffnx Request @t{.\name\} \arg\ @rqindex \name\ @end macro @macro endDefreq @end deffn @end macro @c definition of escapes @macro Defesc{name, delimI, arg, delimII} @deffn Escape @t{\name\\delimI\}@Var{\arg\}@t{\delimII\} @esindex \name\ @end macro @macro DefescList{name, delimI, arg, delimII} @deffn Escape @t{\name\\delimI\}@Var{\arg\}@t{\delimII\} @defdummy @esindex \name\ @end macro @macro DefescItem{name, delimI, arg, delimII} @deffnx Escape @t{\name\\delimI\}@Var{\arg\}@t{\delimII\} @defdummy @esindex \name\ @end macro @macro DefescListEnd{name, delimI, arg, delimII} @deffnx Escape @t{\name\\delimI\}@Var{\arg\}@t{\delimII\} @esindex \name\ @end macro @macro endDefesc @end deffn @end macro @c definition of registers @macro Defreg{name} @deffn Register @t{\\n[\name\]} @vindex \name\ @end macro @macro DefregList{name} @deffn Register @t{\\n[\name\]} @defdummy @vindex \name\ @end macro @macro DefregItem{name} @deffnx Register @t{\\n[\name\]} @defdummy @vindex \name\ @end macro @macro DefregListEnd{name} @deffnx Register @t{\\n[\name\]} @vindex \name\ @end macro @macro endDefreg @end deffn @end macro @c definition of registers specific to macro packages, preprocessors, etc. @macro Defmpreg{name, package} @deffn Register @t{\\n[\name\]} @vindex \name\ @r{[}\package\@r{]} @end macro @macro DefmpregList{name, package} @deffn Register @t{\\n[\name\]} @defdummy @vindex \name\ @r{[}\package\@r{]} @end macro @macro DefmpregItem{name, package} @deffnx Register @t{\\n[\name\]} @defdummy @vindex \name\ @r{[}\package\@r{]} @end macro @macro DefmpregListEnd{name, package} @deffnx Register @t{\\n[\name\]} @vindex \name\ @r{[}\package\@r{]} @end macro @macro endDefmpreg @end deffn @end macro @c definition of macros @macro Defmac{name, arg, package} @defmac @t{.\name\} \arg\ @maindex \name\ @r{[}\package\@r{]} @end macro @macro DefmacList{name, arg, package} @defmac @t{.\name\} \arg\ @defdummy @maindex \name\ @r{[}\package\@r{]} @end macro @macro DefmacItem{name, arg, package} @defmacx @t{.\name\} \arg\ @defdummy @maindex \name\ @r{[}\package\@r{]} @end macro @macro DefmacListEnd{name, arg, package} @defmacx @t{.\name\} \arg\ @maindex \name\ @r{[}\package\@r{]} @end macro @macro endDefmac @end defmac @end macro @c definition of strings @macro Defstr{name, package} @deffn String @t{\\*[\name\]} @stindex \name\ @r{[}\package\@r{]} @end macro @macro DefstrList{name, package} @deffn String @t{\\*[\name\]} @defdummy @stindex \name\ @r{[}\package\@r{]} @end macro @macro DefstrItem{name, package} @deffnx String @t{\\*[\name\]} @defdummy @stindex \name\ @r{[}\package\@r{]} @end macro @macro DefstrListEnd{name, package} @deffnx String @t{\\*[\name\]} @stindex \name\ @r{[}\package\@r{]} @end macro @macro endDefstr @end deffn @end macro @c our example macro @macro Example @example @group @end macro @macro endExample @end group @end example @end macro @c @tex \gdef\angles#1{\angleleft{}\r{#1}\angleright{}} @end tex @macro angles{text} <\text\> @end macro @c a <= sign @tex \gdef\LE{\le} @end tex @macro LE <= @end macro @c We need special parentheses and brackets: @c @c . Real parentheses in @deffn produce an error while compiling with @c TeX. @c . Real brackets use the wrong font in @deffn, overriding @t{}. @c @c Since macros aren't expanded in @deffn during -E, the following @c definitions are for non-TeX only. @c @c This is true for texinfo 4.0. @macro lparen ( @end macro @macro rparen ) @end macro @macro lbrack [ @end macro @macro rbrack ] @end macro @tex \gdef\gobblefirst#1#2{#2} \gdef\putwordAppendix{\gobblefirst} @end tex @c Note: We say `Roman numerals' but `roman font'. @dircategory Typesetting @direntry * Groff: (groff). The GNU troff document formatting system. @end direntry @titlepage @title groff @subtitle The GNU implementation of @code{troff} @subtitle Edition 1.19.1 @subtitle Spring 2004 @author by Trent A.@tie{}Fisher @author and Werner Lemberg (@email{bug-groff@@gnu.org}) @page @vskip 0pt plus 1filll @insertcopying @end titlepage @contents @ifinfo @node Top, Introduction, (dir), (dir) @top GNU troff @insertcopying @end ifinfo @ifhtml @node Top, Introduction, (dir), (dir) @top GNU troff @insertcopying @end ifhtml @menu * Introduction:: * Invoking groff:: * Tutorial for Macro Users:: * Macro Packages:: * gtroff Reference:: * Preprocessors:: * Output Devices:: * File formats:: * Installation:: * Copying This Manual:: * Request Index:: * Escape Index:: * Operator Index:: * Register Index:: * Macro Index:: * String Index:: * Glyph Name Index:: * Font File Keyword Index:: * Program and File Index:: * Concept Index:: @end menu @c ===================================================================== @c ===================================================================== @node Introduction, Invoking groff, Top, Top @chapter Introduction @cindex introduction GNU @code{troff} (or @code{groff}) is a system for typesetting documents. @code{troff} is very flexible and has been in existence (and use) for about 3@tie{}decades. It is quite widespread and firmly entrenched in the @acronym{UNIX} community. @menu * What Is groff?:: * History:: * groff Capabilities:: * Macro Package Intro:: * Preprocessor Intro:: * Output device intro:: * Credits:: @end menu @c ===================================================================== @node What Is groff?, History, Introduction, Introduction @section What Is @code{groff}? @cindex what is @code{groff}? @cindex @code{groff} -- what is it? @code{groff} belongs to an older generation of document preparation systems, which operate more like compilers than the more recent interactive @acronym{WYSIWYG}@footnote{What You See Is What You Get} systems. @code{groff} and its contemporary counterpart, @TeX{}, both work using a @dfn{batch} paradigm: The input (or @dfn{source}) files are normal text files with embedded formatting commands. These files can then be processed by @code{groff} to produce a typeset document on a variety of devices. Likewise, @code{groff} should not be confused with a @dfn{word processor}, since that term connotes an integrated system that includes an editor and a text formatter. Also, many word processors follow the @acronym{WYSIWYG} paradigm discussed earlier. Although @acronym{WYSIWYG} systems may be easier to use, they have a number of disadvantages compared to @code{troff}: @itemize @bullet @item They must be used on a graphics display to work on a document. @item Most of the @acronym{WYSIWYG} systems are either non-free or are not very portable. @item @code{troff} is firmly entrenched in all @acronym{UNIX} systems. @item It is difficult to have a wide range of capabilities available within the confines of a GUI/window system. @item It is more difficult to make global changes to a document. @end itemize @quotation ``GUIs normally make it simple to accomplish simple actions and impossible to accomplish complex actions.'' --Doug Gwyn (22/Jun/91 in @code{comp.unix.wizards}) @end quotation @c ===================================================================== @node History, groff Capabilities, What Is groff?, Introduction @section History @cindex history @cindex @code{runoff}, the program @cindex @code{rf}, the program @code{troff} can trace its origins back to a formatting program called @code{runoff}, written by J.@tie{}E.@tie{}Saltzer, which ran on MIT's CTSS operating system in the mid-sixties. This name came from the common phrase of the time ``I'll run off a document.'' Bob Morris ported it to the 635 architecture and called the program @code{roff} (an abbreviation of @code{runoff}). It was rewritten as @code{rf} for the @w{PDP-7} (before having @acronym{UNIX}), and at the same time (1969), Doug McIllroy rewrote an extended and simplified version of @code{roff} in the @acronym{BCPL} programming language. @cindex @code{roff}, the program The first version of @acronym{UNIX} was developed on a @w{PDP-7} which was sitting around Bell Labs. In 1971 the developers wanted to get a @w{PDP-11} for further work on the operating system. In order to justify the cost for this system, they proposed that they would implement a document formatting system for the @acronym{AT&T} patents division. This first formatting program was a reimplementation of McIllroy's @code{roff}, written by J.@tie{}F.@tie{}Ossanna. @cindex @code{nroff}, the program When they needed a more flexible language, a new version of @code{roff} called @code{nroff} (``Newer @code{roff}'') was written. It had a much more complicated syntax, but provided the basis for all future versions. When they got a Graphic Systems CAT Phototypesetter, Ossanna wrote a version of @code{nroff} that would drive it. It was dubbed @code{troff}, for ``typesetter @code{roff}'', although many people have speculated that it actually means ``Times @code{roff}'' because of the use of the Times font family in @code{troff} by default. As such, the name @code{troff} is pronounced `@w{t-roff}' rather than `trough'. With @code{troff} came @code{nroff} (they were actually the same program except for some @samp{#ifdef}s), which was for producing output for line printers and character terminals. It understood everything @code{troff} did, and ignored the commands which were not applicable (e.g.@: font changes). Since there are several things which cannot be done easily in @code{troff}, work on several preprocessors began. These programs would transform certain parts of a document into @code{troff}, which made a very natural use of pipes in @acronym{UNIX}. The @code{eqn} preprocessor allowed mathematical formul@ae{} to be specified in a much simpler and more intuitive manner. @code{tbl} is a preprocessor for formatting tables. The @code{refer} preprocessor (and the similar program, @code{bib}) processes citations in a document according to a bibliographic database. Unfortunately, Ossanna's @code{troff} was written in @w{PDP-11} assembly language and produced output specifically for the CAT phototypesetter. He rewrote it in C, although it was now 7000@tie{}lines of uncommented code and still dependent on the CAT. As the CAT became less common, and was no longer supported by the manufacturer, the need to make it support other devices became a priority. However, before this could be done, Ossanna was killed in a car accident. @pindex ditroff @cindex @code{ditroff}, the program So, Brian Kernighan took on the task of rewriting @code{troff}. The newly rewritten version produced device independent code which was very easy for postprocessors to read and translate to the appropriate printer codes. Also, this new version of @code{troff} (called @code{ditroff} for ``device independent @code{troff}'') had several extensions, which included drawing functions. Due to the additional abilities of the new version of @code{troff}, several new preprocessors appeared. The @code{pic} preprocessor provides a wide range of drawing functions. Likewise the @code{ideal} preprocessor did the same, although via a much different paradigm. The @code{grap} preprocessor took specifications for graphs, but, unlike other preprocessors, produced @code{pic} code. James Clark began work on a GNU implementation of @code{ditroff} in early@tie{}1989. The first version, @code{groff}@tie{}0.3.1, was released June@tie{}1990. @code{groff} included: @itemize @bullet @item A replacement for @code{ditroff} with many extensions. @item The @code{soelim}, @code{pic}, @code{tbl}, and @code{eqn} preprocessors. @item Postprocessors for character devices, @sc{PostScript}, @TeX{} DVI, and X@tie{}Windows. GNU @code{troff} also eliminated the need for a separate @code{nroff} program with a postprocessor which would produce @acronym{ASCII} output. @item A version of the @file{me} macros and an implementation of the @file{man} macros. @end itemize Also, a front-end was included which could construct the, sometimes painfully long, pipelines required for all the post- and preprocessors. Development of GNU @code{troff} progressed rapidly, and saw the additions of a replacement for @code{refer}, an implementation of the @file{ms} and @file{mm} macros, and a program to deduce how to format a document (@code{grog}). It was declared a stable (i.e.@: non-beta) package with the release of version@tie{}1.04 around November@tie{}1991. Beginning in@tie{}1999, @code{groff} has new maintainers (the package was an orphan for a few years). As a result, new features and programs like @code{grn}, a preprocessor for gremlin images, and an output device to produce @acronym{HTML} output have been added. @c ===================================================================== @node groff Capabilities, Macro Package Intro, History, Introduction @section @code{groff} Capabilities @cindex @code{groff} capabilities @cindex capabilities of @code{groff} So what exactly is @code{groff} capable of doing? @code{groff} provides a wide range of low-level text formatting operations. Using these, it is possible to perform a wide range of formatting tasks, such as footnotes, table of contents, multiple columns, etc. Here's a list of the most important operations supported by @code{groff}: @itemize @bullet @item text filling, adjusting, and centering @item hyphenation @item page control @item font and glyph size control @item vertical spacing (e.g.@: double-spacing) @item line length and indenting @item macros, strings, diversions, and traps @item number registers @item tabs, leaders, and fields @item input and output conventions and character translation @item overstrike, bracket, line drawing, and zero-width functions @item local horizontal and vertical motions and the width function @item three-part titles @item output line numbering @item conditional acceptance of input @item environment switching @item insertions from the standard input @item input/output file switching @item output and error messages @end itemize @c ===================================================================== @node Macro Package Intro, Preprocessor Intro, groff Capabilities, Introduction @section Macro Packages @cindex macro packages Since @code{groff} provides such low-level facilities, it can be quite difficult to use by itself. However, @code{groff} provides a @dfn{macro} facility to specify how certain routine operations (e.g.@tie{}starting paragraphs, printing headers and footers, etc.)@: should be done. These macros can be collected together into a @dfn{macro package}. There are a number of macro packages available; the most common (and the ones described in this manual) are @file{man}, @file{mdoc}, @file{me}, @file{ms}, and @file{mm}. @c ===================================================================== @node Preprocessor Intro, Output device intro, Macro Package Intro, Introduction @section Preprocessors @cindex preprocessors Although @code{groff} provides most functions needed to format a document, some operations would be unwieldy (e.g.@: to draw pictures). Therefore, programs called @dfn{preprocessors} were written which understand their own language and produce the necessary @code{groff} operations. These preprocessors are able to differentiate their own input from the rest of the document via markers. To use a preprocessor, @acronym{UNIX} pipes are used to feed the output from the preprocessor into @code{groff}. Any number of preprocessors may be used on a given document; in this case, the preprocessors are linked together into one pipeline. However, with @code{groff}, the user does not need to construct the pipe, but only tell @code{groff} what preprocessors to use. @code{groff} currently has preprocessors for producing tables (@code{tbl}), typesetting equations (@code{eqn}), drawing pictures (@code{pic} and @code{grn}), and for processing bibliographies (@code{refer}). An associated program which is useful when dealing with preprocessors is @code{soelim}. A free implementation of @code{grap}, a preprocessor for drawing graphs, can be obtained as an extra package; @code{groff} can use @code{grap} also. There are other preprocessors in existence, but, unfortunately, no free implementations are available. Among them are preprocessors for drawing mathematical pictures (@code{ideal}) and chemical structures (@code{chem}). @c ===================================================================== @node Output device intro, Credits, Preprocessor Intro, Introduction @section Output Devices @cindex postprocessors @cindex output devices @cindex devices for output @code{groff} actually produces device independent code which may be fed into a postprocessor to produce output for a particular device. Currently, @code{groff} has postprocessors for @sc{PostScript} devices, character terminals, X@tie{}Windows (for previewing), @TeX{} DVI format, HP LaserJet@tie{}4 and Canon LBP printers (which use @acronym{CAPSL}), and @acronym{HTML}. @c ===================================================================== @node Credits, , Output device intro, Introduction @section Credits @cindex credits Large portions of this manual were taken from existing documents, most notably, the manual pages for the @code{groff} package by James Clark, and Eric Allman's papers on the @file{me} macro package. The section on the @file{man} macro package is partly based on Susan@tie{}G.@: Kleinmann's @file{groff_man} manual page written for the Debian GNU/Linux system. Larry Kollar contributed the section in the @file{ms} macro package. @c ===================================================================== @c ===================================================================== @node Invoking groff, Tutorial for Macro Users, Introduction, Top @chapter Invoking @code{groff} @cindex invoking @code{groff} @cindex @code{groff} invocation This section focuses on how to invoke the @code{groff} front end. This front end takes care of the details of constructing the pipeline among the preprocessors, @code{gtroff} and the postprocessor. It has become a tradition that GNU programs get the prefix @samp{g} to distinguish it from its original counterparts provided by the host (see @ref{Environment}, for more details). Thus, for example, @code{geqn} is GNU @code{eqn}. On operating systems like GNU/Linux or the Hurd, which don't contain proprietary versions of @code{troff}, and on MS-DOS/MS-Windows, where @code{troff} and associated programs are not available at all, this prefix is omitted since GNU @code{troff} is the only used incarnation of @code{troff}. Exception: @samp{groff} is never replaced by @samp{roff}. In this document, we consequently say @samp{gtroff} when talking about the GNU @code{troff} program. All other implementations of @code{troff} are called @acronym{AT&T} @code{troff} which is the common origin of all @code{troff} derivates (with more or less compatible changes). Similarly, we say @samp{gpic}, @samp{geqn}, etc. @menu * Groff Options:: * Environment:: * Macro Directories:: * Font Directories:: * Paper Size:: * Invocation Examples:: @end menu @c ===================================================================== @node Groff Options, Environment, Invoking groff, Invoking groff @section Options @cindex options @pindex groff @pindex gtroff @pindex gpic @pindex geqn @pindex ggrn @pindex grap @pindex gtbl @pindex grefer @pindex gsoelim @code{groff} normally runs the @code{gtroff} program and a postprocessor appropriate for the selected device. The default device is @samp{ps} (but it can be changed when @code{groff} is configured and built). It can optionally preprocess with any of @code{gpic}, @code{geqn}, @code{gtbl}, @code{ggrn}, @code{grap}, @code{grefer}, or @code{gsoelim}. This section only documents options to the @code{groff} front end. Many of the arguments to @code{groff} are passed on to @code{gtroff}, therefore those are also included. Arguments to pre- or postprocessors can be found in @ref{Invoking gpic}, @ref{Invoking geqn}, @ref{Invoking gtbl}, @ref{Invoking ggrn}, @ref{Invoking grefer}, @ref{Invoking gsoelim}, @ref{Invoking grotty}, @ref{Invoking grops}, @ref{Invoking grohtml}, @ref{Invoking grodvi}, @ref{Invoking grolj4}, @ref{Invoking grolbp}, and @ref{Invoking gxditview}. The command line format for @code{groff} is: @Example groff [ -abceghilpstvzCEGNRSUVXZ ] [ -F@var{dir} ] [ -m@var{name} ] [ -T@var{def} ] [ -f@var{fam} ] [ -w@var{name} ] [ -W@var{name} ] [ -M@var{dir} ] [ -d@var{cs} ] [ -r@var{cn} ] [ -n@var{num} ] [ -o@var{list} ] [ -P@var{arg} ] [ -L@var{arg} ] [ -I@var{dir} ] [ @var{files}@dots{} ] @endExample The command line format for @code{gtroff} is as follows. @Example gtroff [ -abcivzCERU ] [ -w@var{name} ] [ -W@var{name} ] [ -d@var{cs} ] [ -f@var{fam} ] [ -m@var{name} ] [ -n@var{num} ] [ -o@var{list} ] [ -r@var{cn} ] [ -T@var{name} ] [ -F@var{dir} ] [ -M@var{dir} ] [ @var{files}@dots{} ] @endExample @noindent Obviously, many of the options to @code{groff} are actually passed on to @code{gtroff}. Options without an argument can be grouped behind a single@tie{}@option{-}. A filename of@tie{}@file{-} denotes the standard input. It is possible to have whitespace between an option and its parameter. The @code{grog} command can be used to guess the correct @code{groff} command to format a file. Here's the description of the command-line options: @cindex command-line options @table @samp @item -h Print a help message. @item -e Preprocess with @code{geqn}. @item -t Preprocess with @code{gtbl}. @item -g Preprocess with @code{ggrn}. @item -G Preprocess with @code{grap}. @item -p Preprocess with @code{gpic}. @item -s Preprocess with @code{gsoelim}. @item -c Suppress color output. @item -R Preprocess with @code{grefer}. No mechanism is provided for passing arguments to @code{grefer} because most @code{grefer} options have equivalent commands which can be included in the file. @xref{grefer}, for more details. @pindex troffrc @pindex troffrc-end Note that @code{gtroff} also accepts a @option{-R} option, which is not accessible via @code{groff}. This option prevents the loading of the @file{troffrc} and @file{troffrc-end} files. @item -v Make programs run by @code{groff} print out their version number. @item -V Print the pipeline on @code{stdout} instead of executing it. If specified more than once, print the pipeline on @code{stderr} and execute it. @item -z Suppress output from @code{gtroff}. Only error messages are printed. @item -Z Do not postprocess the output of @code{gtroff}. Normally @code{groff} automatically runs the appropriate postprocessor. @item -P@var{arg} Pass @var{arg} to the postprocessor. Each argument should be passed with a separate @option{-P} option. Note that @code{groff} does not prepend @samp{-} to @var{arg} before passing it to the postprocessor. @item -l Send the output to a spooler for printing. The command used for this is specified by the @code{print} command in the device description file (see @ref{Font Files}, for more info). If not present, @option{-l} is ignored. @item -L@var{arg} Pass @var{arg} to the spooler. Each argument should be passed with a separate @option{-L} option. Note that @code{groff} does not prepend a @samp{-} to @var{arg} before passing it to the postprocessor. If the @code{print} keyword in the device description file is missing, @option{-L} is ignored. @item -T@var{dev} Prepare output for device @var{dev}. The default device is @samp{ps}, unless changed when @code{groff} was configured and built. The following are the output devices currently available: @table @code @item ps For @sc{PostScript} printers and previewers. @item dvi For @TeX{} DVI format. @item X75 For a 75@dmn{dpi} X11 previewer. @item X75-12 For a 75@dmn{dpi} X11 previewer with a 12@dmn{pt} base font in the document. @item X100 For a 100@dmn{dpi} X11 previewer. @item X100-12 For a 100@dmn{dpi} X11 previewer with a 12@dmn{pt} base font in the document. @item ascii @cindex encoding, output, @acronym{ASCII} @cindex @acronym{ASCII}, output encoding @cindex output encoding, @acronym{ASCII} For typewriter-like devices using the (7-bit) @acronym{ASCII} character set. @item latin1 @cindex encoding, output, @w{latin-1} (ISO @w{8859-1}) @cindex @w{latin-1} (ISO @w{8859-1}), output encoding @cindex ISO @w{8859-1} (@w{latin-1}), output encoding @cindex output encoding, @w{latin-1} (ISO @w{8859-1}) For typewriter-like devices that support the @w{Latin-1} (ISO@tie{}@w{8859-1}) character set. @item utf8 @cindex encoding, output, @w{utf-8} @cindex @w{utf-8}, output encoding @cindex output encoding, @w{utf-8} For typewriter-like devices which use the Unicode (ISO@tie{}10646) character set with @w{UTF-8} encoding. @item cp1047 @cindex encoding, output, @acronym{EBCDIC} @cindex @acronym{EBCDIC}, output encoding @cindex output encoding, @acronym{EBCDIC} @cindex encoding, output, cp1047 @cindex cp1047, output encoding @cindex output encoding, cp1047 @cindex IBM cp1047 output encoding For typewriter-like devices which use the @acronym{EBCDIC} encoding IBM cp1047. @item lj4 For HP LaserJet4-compatible (or other PCL5-compatible) printers. @item lbp For Canon @acronym{CAPSL} printers (@w{LBP-4} and @w{LBP-8} series laser printers). @pindex pre-grohtml @pindex post-grohtml @cindex @code{grohtml}, the program @item html To produce @acronym{HTML} output. Note that the @acronym{HTML} driver consists of two parts, a preprocessor (@code{pre-grohtml}) and a postprocessor (@code{post-grohtml}). @end table @cindex output device name string register (@code{.T}) @cindex output device usage number register (@code{.T}) The predefined @code{gtroff} string register @code{.T} contains the current output device; the read-only number register @code{.T} is set to@tie{}1 if this option is used (which is always true if @code{groff} is used to call @code{gtroff}). @xref{Built-in Registers}. The postprocessor to be used for a device is specified by the @code{postpro} command in the device description file. (@xref{Font Files}, for more info.) This can be overridden with the @option{-X} option. @item -X Preview with @code{gxditview} instead of using the usual postprocessor. This is unlikely to produce good results except with @option{-Tps}. Note that this is not the same as using @option{-TX75} or @option{-TX100} to view a document with @code{gxditview}: The former uses the metrics of the specified device, whereas the latter uses X-specific fonts and metrics. @item -N Don't allow newlines with @code{eqn} delimiters. This is the same as the @option{-N} option in @code{geqn}. @item -S @cindex @code{open} request, and safer mode @cindex @code{opena} request, and safer mode @cindex @code{pso} request, and safer mode @cindex @code{sy} request, and safer mode @cindex @code{pi} request, and safer mode @cindex safer mode @cindex mode, safer Safer mode. Pass the @option{-S} option to @code{gpic} and disable the @code{open}, @code{opena}, @code{pso}, @code{sy}, and @code{pi} requests. For security reasons, this is enabled by default. @item -U @cindex mode, unsafe @cindex unsafe mode Unsafe mode. This enables the @code{open}, @code{opena}, @code{pso}, @code{sy}, and @code{pi} requests. @item -a @cindex @acronym{ASCII} approximation output register (@code{.A}) Generate an @acronym{ASCII} approximation of the typeset output. The read-only register @code{.A} is then set to@tie{}1. @xref{Built-in Registers}. A typical example is @Example groff -a -man -Tdvi troff.man | less @endExample @noindent which shows how lines are broken for the DVI device. Note that this option is rather useless today since graphic output devices are available virtually everywhere. @item -b Print a backtrace with each warning or error message. This backtrace should help track down the cause of the error. The line numbers given in the backtrace may not always be correct: @code{gtroff} can get confused by @code{as} or @code{am} requests while counting line numbers. @item -i Read the standard input after all the named input files have been processed. @item -w@var{name} Enable warning @var{name}. Available warnings are described in @ref{Debugging}. Multiple @option{-w} options are allowed. @item -W@var{name} Inhibit warning @var{name}. Multiple @option{-W} options are allowed. @item -E Inhibit all error messages. @item -C Enable compatibility mode. @xref{Implementation Differences}, for the list of incompatibilities between @code{groff} and @acronym{AT&T} @code{troff}. @item -d@var{c}@var{s} @itemx -d@var{name}=@var{s} Define @var{c} or @var{name} to be a string@tie{}@var{s}. @var{c}@tie{}must be a one-letter name; @var{name} can be of arbitrary length. All string assignments happen before loading any macro file (including the start-up file). @item -f@var{fam} Use @var{fam} as the default font family. @xref{Font Families}. @item -m@var{name} Read in the file @file{@var{name}.tmac}. Normally @code{groff} searches for this in its macro directories. If it isn't found, it tries @file{tmac.@var{name}} (searching in the same directories). @item -n@var{num} Number the first page @var{num}. @item -o@var{list} @cindex print current page register (@code{.P}) Output only pages in @var{list}, which is a comma-separated list of page ranges; @samp{@var{n}} means print page@tie{}@var{n}, @samp{@var{m}-@var{n}} means print every page between @var{m} and@tie{}@var{n}, @samp{-@var{n}} means print every page up to@tie{}@var{n}, @samp{@var{n}-} means print every page beginning with@tie{}@var{n}. @code{gtroff} exits after printing the last page in the list. All the ranges are inclusive on both ends. Within @code{gtroff}, this information can be extracted with the @samp{.P} register. @xref{Built-in Registers}. If your document restarts page numbering at the beginning of each chapter, then @code{gtroff} prints the specified page range for each chapter. @item -r@var{c}@var{n} @itemx -r@var{name}=@var{n} Set number register@tie{}@var{c} or @var{name} to the value@tie{}@var{n}. @var{c}@tie{}must be a one-letter name; @var{name} can be of arbitrary length. @var{n}@tie{}can be any @code{gtroff} numeric expression. All register assignments happen before loading any macro file (including the start-up file). @item -F@var{dir} Search @file{@var{dir}} for subdirectories @file{dev@var{name}} (@var{name} is the name of the device), for the @file{DESC} file, and for font files before looking in the standard directories (@pxref{Font Directories}). This option is passed to all pre- and postprocessors using the @env{GROFF_FONT_PATH} environment variable. @item -M@var{dir} Search directory @file{@var{dir}} for macro files before the standard directories (@pxref{Macro Directories}). @item -I@var{dir} This option may be used to specify a directory to search for files. It is passed to the following programs: @itemize @item @code{gsoelim} (see @ref{gsoelim} for more details); it also implies @code{groff}'s @option{-s} option. @item @code{gtroff}; it is used to search files named in the @code{psbb} and @code{so} requests. @item @code{grops}; it is used to search files named in the @w{@code{\X'ps: import}} and @w{@code{\X'ps: file}} escapes. @end itemize The current directory is always searched first. This option may be specified more than once; the directories will be searched in the order specified. No directory search is performed for files specified using an absolute path. @end table @c ===================================================================== @node Environment, Macro Directories, Groff Options, Invoking groff @section Environment @cindex environment variables @cindex variables in environment There are also several environment variables (of the operating system, not within @code{gtroff}) which can modify the behavior of @code{groff}. @table @code @item GROFF_COMMAND_PREFIX @tindex GROFF_COMMAND_PREFIX@r{, environment variable} @cindex command prefix @cindex prefix, for commands If this is set to@tie{}@var{X}, then @code{groff} runs @code{@var{X}troff} instead of @code{gtroff}. This also applies to @code{tbl}, @code{pic}, @code{eqn}, @code{grn}, @code{refer}, and @code{soelim}. It does not apply to @code{grops}, @code{grodvi}, @code{grotty}, @code{pre-grohtml}, @code{post-grohtml}, @code{grolj4}, and @code{gxditview}. The default command prefix is determined during the installation process. If a non-GNU troff system is found, prefix @samp{g} is used, none otherwise. @item GROFF_TMAC_PATH @tindex GROFF_TMAC_PATH@r{, environment variable} A colon-separated list of directories in which to search for macro files (before the default directories are tried). @xref{Macro Directories}. @item GROFF_TYPESETTER @tindex GROFF_TYPESETTER@r{, environment variable} The default output device. @item GROFF_FONT_PATH @tindex GROFF_FONT_PATH@r{, environment variable} A colon-separated list of directories in which to search for the @code{dev}@var{name} directory (before the default directories are tried). @xref{Font Directories}. @item GROFF_BIN_PATH @tindex GROFF_BIN_PATH@r{, environment variable} This search path, followed by @code{PATH}, is used for commands executed by @code{groff}. @item GROFF_TMPDIR @tindex GROFF_TMPDIR@r{, environment variable} @tindex TMPDIR@r{, environment variable} The directory in which @code{groff} creates temporary files. If this is not set and @env{TMPDIR} is set, temporary files are created in that directory. Otherwise temporary files are created in a system-dependent default directory (on Unix and GNU/Linux systems, this is usually @file{/tmp}). @code{grops}, @code{grefer}, @code{pre-grohtml}, and @code{post-grohtml} can create temporary files in this directory. @end table Note that MS-DOS and MS-Windows ports of @code{groff} use semi-colons, rather than colons, to separate the directories in the lists described above. @c ===================================================================== @node Macro Directories, Font Directories, Environment, Invoking groff @section Macro Directories @cindex macro directories @cindex directories for macros @cindex searching macros @cindex macros, searching All macro file names must be named @code{@var{name}.tmac} or @code{tmac.@var{name}} to make the @option{-m@var{name}} command line option work. The @code{mso} request doesn't have this restriction; any file name can be used, and @code{gtroff} won't try to append or prepend the @samp{tmac} string. @cindex tmac, directory @cindex directory, for tmac files @cindex tmac, path @cindex path, for tmac files @cindex searching macro files @cindex macro files, searching @cindex files, macro, searching Macro files are kept in the @dfn{tmac directories}, all of which constitute the @dfn{tmac path}. The elements of the search path for macro files are (in that order): @itemize @bullet @item The directories specified with @code{gtroff}'s or @code{groff}'s @option{-M} command line option. @item @tindex GROFF_TMAC_PATH@r{, environment variable} The directories given in the @env{GROFF_TMAC_PATH} environment variable. @item @cindex safer mode @cindex mode, safer @cindex unsafe mode @cindex mode, unsafe @cindex current directory @cindex directory, current The current directory (only if in unsafe mode using the @option{-U} command line switch). @item @cindex home directory @cindex directory, home The home directory. @item @cindex site-specific directory @cindex directory, site-specific @cindex platform-specific directory @cindex directory, platform-specific A platform-dependent directory, a site-specific (platform-independent) directory, and the main tmac directory; the default locations are @Example /usr/local/lib/groff/site-tmac /usr/local/share/groff/site-tmac /usr/local/share/groff/1.18.2/tmac @endExample @noindent assuming that the version of @code{groff} is 1.18.2, and the installation prefix was @file{/usr/local}. It is possible to fine-tune those directories during the installation process. @end itemize @c ===================================================================== @node Font Directories, Paper Size, Macro Directories, Invoking groff @section Font Directories @cindex font directories @cindex directories for fonts @cindex searching fonts @cindex fonts, searching Basically, there is no restriction how font files for @code{groff} are named and how long font names are; however, to make the font family mechanism work (@pxref{Font Families}), fonts within a family should start with the family name, followed by the shape. For example, the Times family uses @samp{T} for the family name and @samp{R}, @samp{B}, @samp{I}, and @samp{BI} to indicate the shapes `roman', `bold', `italic', and `bold italic', respectively. Thus the final font names are @samp{TR}, @samp{TB}, @samp{TI}, and @samp{TBI}. @cindex font path @cindex path, for font files All font files are kept in the @dfn{font directories} which constitute the @dfn{font path}. The file search functions will always append the directory @code{dev}@var{name}, where @var{name} is the name of the output device. Assuming, say, DVI output, and @file{/foo/bar} as a font directory, the font files for @code{grodvi} must be in @file{/foo/bar/devdvi}. The elements of the search path for font files are (in that order): @itemize @bullet @item The directories specified with @code{gtroff}'s or @code{groff}'s @option{-F} command line option. All device drivers and some preprocessors also have this option. @item @tindex GROFF_FONT_PATH@r{, environment variable} The directories given in the @env{GROFF_FONT_PATH} environment variable. @item @cindex site-specific directory @cindex directory, site-specific A site-specific directory and the main font directory; the default locations are @Example /usr/local/share/groff/site-font /usr/local/share/groff/1.18.2/font @endExample @noindent assuming that the version of @code{groff} is 1.18.2, and the installation prefix was @file{/usr/local}. It is possible to fine-tune those directories during the installation process. @end itemize @c ===================================================================== @node Paper Size, Invocation Examples, Font Directories, Invoking groff @section Paper Size @cindex paper size @cindex size, paper @cindex landscape page orientation @cindex orientation, landscape @cindex page orientation, landscape In groff, the page size for @code{gtroff} and for output devices are handled separately. @xref{Page Layout}, for vertical manipulation of the page size. @xref{Line Layout}, for horizontal changes. A default paper size can be set in the device's @file{DESC} file. Most output devices also have a command line option @option{-p} to override the default paper size and option @option{-l} to use landscape orientation. @xref{DESC File Format}, for a description of the @code{papersize} keyword which takes the same argument as @option{-p}. @pindex papersize.tmac @pindex troffrc A convenient shorthand to set a particular paper size for @code{gtroff} is command line option @option{-dpaper=@var{size}}. This defines string @code{paper} which is processed in file @file{papersize.tmac} (loaded in the start-up file @file{troffrc} by default). Possible values for @var{size} are the same as the predefined values for the @code{papersize} keyword (but only in lowercase) except @code{a7}-@code{d7}. An appended @samp{l} (ell) character denotes landscape orientation. For example, use the following for PS output on A4 paper in landscape orientation: @Example groff -Tps -dpaper=a4l -P-pa4 -P-l -ms foo.ms > foo.ps @endExample Note that it is up to the particular macro package to respect default page dimensions set in this way (most do). @c ===================================================================== @node Invocation Examples, , Paper Size, Invoking groff @section Invocation Examples @cindex invocation examples @cindex examples of invocation This section lists several common uses of @code{groff} and the corresponding command lines. @Example groff file @endExample @noindent This command processes @file{file} without a macro package or a preprocessor. The output device is the default, @samp{ps}, and the output is sent to @code{stdout}. @Example groff -t -mandoc -Tascii file | less @endExample @noindent This is basically what a call to the @code{man} program does. @code{gtroff} processes the manual page @file{file} with the @file{mandoc} macro file (which in turn either calls the @file{man} or the @file{mdoc} macro package), using the @code{tbl} preprocessor and the @acronym{ASCII} output device. Finally, the @code{less} pager displays the result. @Example groff -X -m me file @endExample @noindent Preview @file{file} with @code{gxditview}, using the @file{me} macro package. Since no @option{-T} option is specified, use the default device (@samp{ps}). Note that you can either say @w{@samp{-m me}} or @w{@samp{-me}}; the latter is an anachronism from the early days of @acronym{UNIX}.@footnote{The same is true for the other main macro packages that come with @code{groff}: @file{man}, @file{mdoc}, @file{ms}, @file{mm}, and @file{mandoc}. This won't work in general; for example, to load @file{trace.tmac}, either @samp{-mtrace} or @w{@samp{-m trace}} must be used.} @Example groff -man -rD1 -z file @endExample @noindent Check @file{file} with the @file{man} macro package, forcing double-sided printing -- don't produce any output. @menu * grog:: @end menu @c --------------------------------------------------------------------- @node grog, , Invocation Examples, Invocation Examples @subsection @code{grog} @pindex grog @code{grog} reads files, guesses which of the @code{groff} preprocessors and/or macro packages are required for formatting them, and prints the @code{groff} command including those options on the standard output. It generates one or more of the options @option{-e}, @option{-man}, @option{-me}, @option{-mm}, @option{-mom}, @option{-ms}, @option{-mdoc}, @option{-mdoc-old}, @option{-p}, @option{-R}, @option{-g}, @option{-G}, @option{-s}, and @option{-t}. A special file name@tie{}@file{-} refers to the standard input. Specifying no files also means to read the standard input. Any specified options are included in the printed command. No space is allowed between options and their arguments. The only options recognized are @option{-C} (which is also passed on) to enable compatibility mode, and @option{-v} to print the version number and exit. For example, @Example grog -Tdvi paper.ms @endExample @noindent guesses the appropriate command to print @file{paper.ms} and then prints it to the command line after adding the @option{-Tdvi} option. For direct execution, enclose the call to @code{grog} in backquotes at the @acronym{UNIX} shell prompt: @Example `grog -Tdvi paper.ms` > paper.dvi @endExample @noindent As seen in the example, it is still necessary to redirect the output to something meaningful (i.e.@: either a file or a pager program like @code{less}). @c ===================================================================== @c ===================================================================== @node Tutorial for Macro Users, Macro Packages, Invoking groff, Top @chapter Tutorial for Macro Users @cindex tutorial for macro users @cindex macros, tutorial for users @cindex user's tutorial for macros @cindex user's macro tutorial Most users tend to use a macro package to format their papers. This means that the whole breadth of @code{groff} is not necessary for most people. This chapter covers the material needed to efficiently use a macro package. @menu * Basics:: * Common Features:: @end menu @c ===================================================================== @node Basics, Common Features, Tutorial for Macro Users, Tutorial for Macro Users @section Basics @cindex basics of macros @cindex macro basics This section covers some of the basic concepts necessary to understand how to use a macro package.@footnote{This section is derived from @cite{Writing Papers with nroff using -me} by Eric P.@tie{}Allman.} References are made throughout to more detailed information, if desired. @code{gtroff} reads an input file prepared by the user and outputs a formatted document suitable for publication or framing. The input consists of text, or words to be printed, and embedded commands (@dfn{requests} and @dfn{escapes}), which tell @code{gtroff} how to format the output. For more detail on this, see @ref{Embedded Commands}. The word @dfn{argument} is used in this chapter to mean a word or number which appears on the same line as a request, and which modifies the meaning of that request. For example, the request @Example .sp @endExample @noindent spaces one line, but @Example .sp 4 @endExample @noindent spaces four lines. The number@tie{}4 is an argument to the @code{sp} request which says to space four lines instead of one. Arguments are separated from the request and from each other by spaces (@emph{no} tabs). More details on this can be found in @ref{Request and Macro Arguments}. The primary function of @code{gtroff} is to collect words from input lines, fill output lines with those words, justify the right-hand margin by inserting extra spaces in the line, and output the result. For example, the input: @Example Now is the time for all good men to come to the aid of their party. Four score and seven years ago, etc. @endExample @noindent is read, packed onto output lines, and justified to produce: @quotation Now is the time for all good men to come to the aid of their party. Four score and seven years ago, etc. @end quotation @cindex break @cindex line break Sometimes a new output line should be started even though the current line is not yet full; for example, at the end of a paragraph. To do this it is possible to cause a @dfn{break}, which starts a new output line. Some requests cause a break automatically, as normally do blank input lines and input lines beginning with a space. Not all input lines are text to be formatted. Some input lines are requests which describe how to format the text. Requests always have a period (@samp{.}) or an apostrophe (@samp{'}) as the first character of the input line. The text formatter also does more complex things, such as automatically numbering pages, skipping over page boundaries, putting footnotes in the correct place, and so forth. Here are a few hints for preparing text for input to @code{gtroff}. @itemize @bullet @item First, keep the input lines short. Short input lines are easier to edit, and @code{gtroff} packs words onto longer lines anyhow. @item In keeping with this, it is helpful to begin a new line after every comma or phrase, since common corrections are to add or delete sentences or phrases. @item End each sentence with two spaces -- or better, start each sentence on a new line. @code{gtroff} recognizes characters that usually end a sentence, and inserts sentence space accordingly. @item Do not hyphenate words at the end of lines -- @code{gtroff} is smart enough to hyphenate words as needed, but is not smart enough to take hyphens out and join a word back together. Also, words such as ``mother-in-law'' should not be broken over a line, since then a space can occur where not wanted, such as ``@w{mother- in}-law''. @end itemize @cindex double-spacing (@code{ls}) @cindex spacing @code{gtroff} double-spaces output text automatically if you use the request @w{@samp{.ls 2}}. Reactivate single-spaced mode by typing @w{@samp{.ls 1}}.@footnote{If you need finer granularity of the vertical space, use the @code{pvs} request (@pxref{Changing Type Sizes}).} A number of requests allow to change the way the output looks, sometimes called the @dfn{layout} of the output page. Most of these requests adjust the placing of @dfn{whitespace} (blank lines or spaces). @cindex new page (@code{bp}) The @code{bp} request starts a new page, causing a line break. @cindex blank line (@code{sp}) @cindex empty line (@code{sp}) @cindex line, empty (@code{sp}) The request @w{@samp{.sp @var{N}}} leaves @var{N}@tie{}lines of blank space. @var{N}@tie{}can be omitted (meaning skip a single line) or can be of the form @var{N}i (for @var{N}@tie{}inches) or @var{N}c (for @var{N}@tie{}centimeters). For example, the input: @Example .sp 1.5i My thoughts on the subject .sp @endExample @noindent leaves one and a half inches of space, followed by the line ``My thoughts on the subject'', followed by a single blank line (more measurement units are available, see @ref{Measurements}). @cindex centering lines (@code{ce}) @cindex lines, centering (@code{ce}) Text lines can be centered by using the @code{ce} request. The line after @code{ce} is centered (horizontally) on the page. To center more than one line, use @w{@samp{.ce @var{N}}} (where @var{N} is the number of lines to center), followed by the @var{N}@tie{}lines. To center many lines without counting them, type: @Example .ce 1000 lines to center .ce 0 @endExample @noindent The @w{@samp{.ce 0}} request tells @code{groff} to center zero more lines, in other words, stop centering. @cindex line break (@code{br}) @cindex break (@code{br}) All of these requests cause a break; that is, they always start a new line. To start a new line without performing any other action, use @code{br}. @c ===================================================================== @node Common Features, , Basics, Tutorial for Macro Users @section Common Features @cindex common features @cindex features, common @code{gtroff} provides very low-level operations for formatting a document. There are many common routine operations which are done in all documents. These common operations are written into @dfn{macros} and collected into a @dfn{macro package}. All macro packages provide certain common capabilities which fall into the following categories. @menu * Paragraphs:: * Sections and Chapters:: * Headers and Footers:: * Page Layout Adjustment:: * Displays:: * Footnotes and Annotations:: * Table of Contents:: * Indices:: * Paper Formats:: * Multiple Columns:: * Font and Size Changes:: * Predefined Strings:: * Preprocessor Support:: * Configuration and Customization:: @end menu @c --------------------------------------------------------------------- @node Paragraphs, Sections and Chapters, Common Features, Common Features @subsection Paragraphs @cindex paragraphs One of the most common and most used capability is starting a paragraph. There are a number of different types of paragraphs, any of which can be initiated with macros supplied by the macro package. Normally, paragraphs start with a blank line and the first line indented, like the text in this manual. There are also block style paragraphs, which omit the indentation: @Example Some men look at constitutions with sanctimonious reverence, and deem them like the ark of the covenant, too sacred to be touched. @endExample @noindent And there are also indented paragraphs which begin with a tag or label at the margin and the remaining text indented. @Example one This is the first paragraph. Notice how the first line of the resulting paragraph lines up with the other lines in the paragraph. @endExample @Example longlabel This paragraph had a long label. The first character of text on the first line does not line up with the text on second and subsequent lines, although they line up with each other. @endExample A variation of this is a bulleted list. @Example . Bulleted lists start with a bullet. It is possible to use other glyphs instead of the bullet. In nroff mode using the ASCII character set for output, a dot is used instead of a real bullet. @endExample @c --------------------------------------------------------------------- @node Sections and Chapters, Headers and Footers, Paragraphs, Common Features @subsection Sections and Chapters Most macro packages supply some form of section headers. The simplest kind is simply the heading on a line by itself in bold type. Others supply automatically numbered section heading or different heading styles at different levels. Some, more sophisticated, macro packages supply macros for starting chapters and appendices. @c --------------------------------------------------------------------- @node Headers and Footers, Page Layout Adjustment, Sections and Chapters, Common Features @subsection Headers and Footers Every macro package gives some way to manipulate the @dfn{headers} and @dfn{footers} (also called @dfn{titles}) on each page. This is text put at the top and bottom of each page, respectively, which contain data like the current page number, the current chapter title, and so on. Its appearance is not affected by the running text. Some packages allow for different ones on the even and odd pages (for material printed in a book form). The titles are called @dfn{three-part titles}, that is, there is a left-justified part, a centered part, and a right-justified part. An automatically generated page number may be put in any of these fields with the @samp{%} character (see @ref{Page Layout}, for more details). @c --------------------------------------------------------------------- @node Page Layout Adjustment, Displays, Headers and Footers, Common Features @subsection Page Layout Most macro packages let the user specify top and bottom margins and other details about the appearance of the printed pages. @c --------------------------------------------------------------------- @node Displays, Footnotes and Annotations, Page Layout Adjustment, Common Features @subsection Displays @cindex displays @dfn{Displays} are sections of text to be set off from the body of the paper. Major quotes, tables, and figures are types of displays, as are all the examples used in this document. @cindex quotes, major @cindex major quotes @dfn{Major quotes} are quotes which are several lines long, and hence are set in from the rest of the text without quote marks around them. @cindex list A @dfn{list} is an indented, single-spaced, unfilled display. Lists should be used when the material to be printed should not be filled and justified like normal text, such as columns of figures or the examples used in this paper. @cindex keep A @dfn{keep} is a display of lines which are kept on a single page if possible. An example for a keep might be a diagram. Keeps differ from lists in that lists may be broken over a page boundary whereas keeps are not. @cindex keep, floating @cindex floating keep @dfn{Floating keeps} move relative to the text. Hence, they are good for things which are referred to by name, such as ``See figure@tie{}3''. A floating keep appears at the bottom of the current page if it fits; otherwise, it appears at the top of the next page. Meanwhile, the surrounding text `flows' around the keep, thus leaving no blank areas. @c --------------------------------------------------------------------- @node Footnotes and Annotations, Table of Contents, Displays, Common Features @subsection Footnotes and Annotations @cindex footnotes @cindex annotations There are a number of requests to save text for later printing. @dfn{Footnotes} are printed at the bottom of the current page. @cindex delayed text @dfn{Delayed text} is very similar to a footnote except that it is printed when called for explicitly. This allows a list of references to appear (for example) at the end of each chapter, as is the convention in some disciplines. Most macro packages which supply this functionality also supply a means of automatically numbering either type of annotation. @c --------------------------------------------------------------------- @node Table of Contents, Indices, Footnotes and Annotations, Common Features @subsection Table of Contents @cindex table of contents @cindex contents, table of @dfn{Tables of contents} are a type of delayed text having a tag (usually the page number) attached to each entry after a row of dots. The table accumulates throughout the paper until printed, usually after the paper has ended. Many macro packages provide the ability to have several tables of contents (e.g.@: a standard table of contents, a list of tables, etc). @c --------------------------------------------------------------------- @node Indices, Paper Formats, Table of Contents, Common Features @subsection Indices @cindex index, in macro package While some macro packages use the term @dfn{index}, none actually provide that functionality. The facilities they call indices are actually more appropriate for tables of contents. @pindex makeindex To produce a real index in a document, external tools like the @code{makeindex} program are necessary. @c --------------------------------------------------------------------- @node Paper Formats, Multiple Columns, Indices, Common Features @subsection Paper Formats @cindex paper formats Some macro packages provide stock formats for various kinds of documents. Many of them provide a common format for the title and opening pages of a technical paper. The @file{mm} macros in particular provide formats for letters and memoranda. @c --------------------------------------------------------------------- @node Multiple Columns, Font and Size Changes, Paper Formats, Common Features @subsection Multiple Columns Some macro packages (but not @file{man}) provide the ability to have two or more columns on a page. @c --------------------------------------------------------------------- @node Font and Size Changes, Predefined Strings, Multiple Columns, Common Features @subsection Font and Size Changes The built-in font and size functions are not always intuitive, so all macro packages provide macros to make these operations simpler. @c --------------------------------------------------------------------- @node Predefined Strings, Preprocessor Support, Font and Size Changes, Common Features @subsection Predefined Strings Most macro packages provide various predefined strings for a variety of uses; examples are sub- and superscripts, printable dates, quotes and various special characters. @c --------------------------------------------------------------------- @node Preprocessor Support, Configuration and Customization, Predefined Strings, Common Features @subsection Preprocessor Support All macro packages provide support for various preprocessors and may extend their functionality. For example, all macro packages mark tables (which are processed with @code{gtbl}) by placing them between @code{TS} and @code{TE} macros. The @file{ms} macro package has an option, @samp{.TS@tie{}H}, that prints a caption at the top of a new page (when the table is too long to fit on a single page). @c --------------------------------------------------------------------- @node Configuration and Customization, , Preprocessor Support, Common Features @subsection Configuration and Customization Some macro packages provide means of customizing many of the details of how the package behaves. This ranges from setting the default type size to changing the appearance of section headers. @c ===================================================================== @c ===================================================================== @node Macro Packages, gtroff Reference, Tutorial for Macro Users, Top @chapter Macro Packages @cindex macro packages @cindex packages, macros This chapter documents the main macro packages that come with @code{groff}. Different main macro packages can't be used at the same time; for example @Example groff -m man foo.man -m ms bar.doc @endExample @noindent doesn't work. Note that option arguments are processed before non-option arguments; the above (failing) sample is thus reordered to @Example groff -m man -m ms foo.man bar.doc @endExample @menu * man:: * mdoc:: * ms:: * me:: * mm:: @end menu @c ===================================================================== @node man, mdoc, Macro Packages, Macro Packages @section @file{man} @cindex manual pages @cindex man pages @pindex an.tmac @pindex man.tmac @pindex man-old.tmac This is the most popular and probably the most important macro package of @code{groff}. It is easy to use, and a vast majority of manual pages are based on it. @menu * Man options:: * Man usage:: * Man font macros:: * Miscellaneous man macros:: * Predefined man strings:: * Preprocessors in man pages:: * Optional man extensions:: @end menu @c --------------------------------------------------------------------- @node Man options, Man usage, man, man @subsection Options The command line format for using the @file{man} macros with @code{groff} is: @Example groff -m man [ -rLL=@var{length} ] [ -rLT=@var{length} ] [ -rFT=@var{dist} ] [ -rcR=1 ] [ -rC1 ] [ -rD1 ] [-rHY=@var{flags} ] [ -rP@var{nnn} ] [ -rS@var{xx} ] [ -rX@var{nnn} ] [ -rIN=@var{length} ] [ -rSN=@var{length} ] [ @var{files}@dots{} ] @endExample @noindent It is possible to use @samp{-man} instead of @w{@samp{-m man}}. @table @code @item -rcR=1 This option (the default if a TTY output device is used) creates a single, very long page instead of multiple pages. Use @code{-rcR=0} to disable it. @item -rC1 If more than one manual page is given on the command line, number the pages continuously, rather than starting each at@tie{}1. @item -rD1 Double-sided printing. Footers for even and odd pages are formatted differently. @item -rFT=@var{dist} Set the position of the footer text to @var{dist}. If positive, the distance is measured relative to the top of the page, otherwise it is relative to the bottom. The default is @minus{}0.5@dmn{i}. @item -rHY=@var{flags} Set hyphenation flags. Possible values are 1@tie{}to hyphenate without restrictions, 2@tie{} to not hyphenate the last word on a page, 4@tie{}to not hyphenate the last two characters of a word, and 8@tie{}to not hyphenate the first two characters of a word. These values are additive; the default is@tie{}14. @item -rIN=@var{length} Set the body text indent to @var{length}. If not specified, the indent defaults to 7@dmn{n} (7@tie{}characters) in nroff mode and 7.2@dmn{n} otherwise. For nroff, this value should always be an integer multiple of unit @samp{n} to get consistent indentation. @item -rLL=@var{length} Set line length to @var{length}. If not specified, the line length defaults to 78@tie{}en in nroff mode (this is 78@tie{}characters per line) and 6.5@tie{}inch otherwise. @item -rLT=@var{length} Set title length to @var{length}. If not specified, the title length defaults to the line length. @item -rP@var{nnn} Page numbering starts with @var{nnn} rather than with@tie{}1. @item -rS@var{xx} Use @var{xx} (which can be 10, 11, or@tie{}12@dmn{pt}) as the base document font size instead of the default value of@tie{}10@dmn{pt}. @item -rSN=@var{length} Set the indent for sub-subheadings to @var{length}. If not specified, the indent defaults to 3@dmn{n}. @item -rX@var{nnn} After page @var{nnn}, number pages as @var{nnn}a, @var{nnn}b, @var{nnn}c, etc. For example, the option @option{-rX2} produces the following page numbers: 1, 2, 2a, 2b, 2c, etc. @end table @c --------------------------------------------------------------------- @node Man usage, Man font macros, Man options, man @subsection Usage @cindex @code{man} macros @cindex macros for manual pages [@code{man}] @pindex man.local This section describes the available macros for manual pages. For further customization, put additional macros and requests into the file @file{man.local} which is loaded immediately after the @file{man} package. @Defmac {TH, title section [@Var{extra1} [@Var{extra2} [@Var{extra3}]]], man} Set the title of the man page to @var{title} and the section to @var{section}, which must have a value between 1 and@tie{}8. The value of @var{section} may also have a string appended, e.g.@: @samp{.pm}, to indicate a specific subsection of the man pages. Both @var{title} and @var{section} are positioned at the left and right in the header line (with @var{section} in parentheses immediately appended to @var{title}. @var{extra1} is positioned in the middle of the footer line. @var{extra2} is positioned at the left in the footer line (or at the left on even pages and at the right on odd pages if double-sided printing is active). @var{extra3} is centered in the header line. For @acronym{HTML} output, headers and footers are completely suppressed. Additionally, this macro starts a new page; the new line number is@tie{}1 again (except if the @option{-rC1} option is given on the command line) -- this feature is intended only for formatting multiple man pages; a single man page should contain exactly one @code{TH} macro at the beginning of the file. @endDefmac @Defmac {SH, [@Var{heading}], man} Set up an unnumbered section heading sticking out to the left. Prints out all the text following @code{SH} up to the end of the line (or the text in the next line if there is no argument to @code{SH}) in bold face (or the font specified by the string @code{HF}), one size larger than the base document size. Additionally, the left margin and the indentation for the following text is reset to its default value. @endDefmac @Defmac {SS, [@Var{heading}], man} Set up an unnumbered (sub)section heading. Prints out all the text following @code{SS} up to the end of the line (or the text in the next line if there is no argument to @code{SS}) in bold face (or the font specified by the string @code{HF}), at the same size as the base document size. Additionally, the left margin and the indentation for the following text is reset to its default value. @endDefmac @Defmac {TP, [@Var{nnn}], man} Set up an indented paragraph with label. The indentation is set to @var{nnn} if that argument is supplied (the default unit is @samp{n} if omitted), otherwise it is set to the previous indentation value specified with @code{TP}, @code{IP}, or @code{HP} (or to the default value if none of them have been used yet). The first line of text following this macro is interpreted as a string to be printed flush-left, as it is appropriate for a label. It is not interpreted as part of a paragraph, so there is no attempt to fill the first line with text from the following input lines. Nevertheless, if the label is not as wide as the indentation the paragraph starts at the same line (but indented), continuing on the following lines. If the label is wider than the indentation the descriptive part of the paragraph begins on the line following the label, entirely indented. Note that neither font shape nor font size of the label is set to a default value; on the other hand, the rest of the text has default font settings. @endDefmac @DefmacList {LP, , man} @DefmacItem {PP, , man} @DefmacListEnd {P, , man} These macros are mutual aliases. Any of them causes a line break at the current position, followed by a vertical space downwards by the amount specified by the @code{PD} macro. The font size and shape are reset to the default value (10@dmn{pt} roman if no @option{-rS} option is given on the command line). Finally, the current left margin and the indentation is restored. @endDefmac @Defmac {IP, [@Var{designator} [@Var{nnn}]], man} Set up an indented paragraph, using @var{designator} as a tag to mark its beginning. The indentation is set to @var{nnn} if that argument is supplied (default unit is @samp{n}), otherwise it is set to the previous indentation value specified with @code{TP}, @code{IP}, or @code{HP} (or the default value if none of them have been used yet). Font size and face of the paragraph (but not the designator) are reset to their default values. To start an indented paragraph with a particular indentation but without a designator, use @samp{""} (two double quotes) as the first argument of @code{IP}. For example, to start a paragraph with bullets as the designator and 4@tie{}en indentation, write @Example .IP \(bu 4 @endExample @endDefmac @Defmac {HP, [@Var{nnn}], man} @cindex hanging indentation [@code{man}] @cindex @code{man} macros, hanging indentation Set up a paragraph with hanging left indentation. The indentation is set to @var{nnn} if that argument is supplied (default unit is @samp{n}), otherwise it is set to the previous indentation value specified with @code{TP}, @code{IP}, or @code{HP} (or the default value if non of them have been used yet). Font size and face are reset to their default values. @endDefmac @Defmac {RS, [@Var{nnn}], man} @cindex left margin, how to move [@code{man}] @cindex @code{man} macros, moving left margin Move the left margin to the right by the value @var{nnn} if specified (default unit is @samp{n}); otherwise it is set to the previous indentation value specified with @code{TP}, @code{IP}, or @code{HP} (or to the default value if none of them have been used yet). The indentation value is then set to the default. Calls to the @code{RS} macro can be nested. @endDefmac @Defmac {RE, [@Var{nnn}], man} Move the left margin back to level @var{nnn}, restoring the previous left margin. If no argument is given, it moves one level back. The first level (i.e., no call to @code{RS} yet) has number@tie{}1, and each call to @code{RS} increases the level by@tie{}1. @endDefmac @cindex line breaks, with vertical space [@code{man}] @cindex @code{man} macros, line breaks with vertical space To summarize, the following macros cause a line break with the insertion of vertical space (which amount can be changed with the @code{PD} macro): @code{SH}, @code{SS}, @code{TP}, @code{LP} (@code{PP}, @code{P}), @code{IP}, and @code{HP}. @cindex line breaks, without vertical space [@code{man}] @cindex @code{man} macros, line breaks without vertical space The macros @code{RS} and @code{RE} also cause a break but do not insert vertical space. @cindex default indentation, resetting [@code{man}] @cindex indentaion, resetting to default [@code{man}] @cindex @code{man} macros, resetting default indentation Finally, the macros @code{SH}, @code{SS}, @code{LP} (@code{PP}, @code{P}), and @code{RS} reset the indentation to its default value. @c --------------------------------------------------------------------- @node Man font macros, Miscellaneous man macros, Man usage, man @subsection Macros to set fonts @cindex font selection [@code{man}] @cindex @code{man} macros, how to set fonts The standard font is roman; the default text size is 10@tie{}point. If command line option @option{-rS=@var{n}} is given, use @var{n}@dmn{pt} as the default text size. @Defmac {SM, [@Var{text}], man} Set the text on the same line or the text on the next line in a font that is one point size smaller than the default font. @endDefmac @Defmac {SB, [@Var{text}], man} @cindex bold face [@code{man}] @cindex @code{man} macros, bold face Set the text on the same line or the text on the next line in bold face font, one point size smaller than the default font. @endDefmac @Defmac {BI, text, man} Set its arguments alternately in bold face and italic, without a space between the arguments. Thus, @Example .BI this "word and" that @endExample @noindent produces ``thisword andthat'' with ``this'' and ``that'' in bold face, and ``word and'' in italics. @endDefmac @Defmac {IB, text, man} Set its arguments alternately in italic and bold face, without a space between the arguments. @endDefmac @Defmac {RI, text, man} Set its arguments alternately in roman and italic, without a space between the arguments. @endDefmac @Defmac {IR, text, man} Set its arguments alternately in italic and roman, without a space between the arguments. @endDefmac @Defmac {BR, text, man} Set its arguments alternately in bold face and roman, without a space between the arguments. @endDefmac @Defmac {RB, text, man} Set its arguments alternately in roman and bold face, without a space between the arguments. @endDefmac @Defmac {B, [@Var{text}], man} Set @var{text} in bold face. If no text is present on the line where the macro is called, then the text of the next line appears in bold face. @endDefmac @Defmac {I, [@Var{text}], man} @cindex italic fonts [@code{man}] @cindex @code{man} macros, italic fonts Set @var{text} in italic. If no text is present on the line where the macro is called, then the text of the next line appears in italic. @endDefmac @c --------------------------------------------------------------------- @node Miscellaneous man macros, Predefined man strings, Man font macros, man @subsection Miscellaneous macros @pindex grohtml @cindex @code{man} macros, default indentation @cindex default indentation [@code{man}] The default indentation is 7.2@dmn{n} in troff mode and 7@dmn{n} in nroff mode except for @code{grohtml} which ignores indentation. @Defmac {DT, , man} @cindex tab stops [@code{man}] @cindex @code{man} macros, tab stops Set tabs every 0.5@tie{}inches. Since this macro is always executed during a call to the @code{TH} macro, it makes sense to call it only if the tab positions have been changed. @endDefmac @Defmac {PD, [@Var{nnn}], man} @cindex empty space before a paragraph [@code{man}] @cindex @code{man} macros, empty space before a paragraph Adjust the empty space before a new paragraph (or section). The optional argument gives the amount of space (default unit is @samp{v}); without parameter, the value is reset to its default value (1@tie{}line in nroff mode, 0.4@dmn{v}@tie{}otherwise). This affects the macros @code{SH}, @code{SS}, @code{TP}, @code{LP} (as well as @code{PP} and @code{P}), @code{IP}, and @code{HP}. @endDefmac The following two macros are included for BSD compatibility. @Defmac {AT, [@Var{system} [@Var{release}]], man} @cindex @code{man}macros, BSD compatibility Alter the footer for use with @acronym{AT&T} manpages. This command exists only for compatibility; don't use it. The first argument @var{system} can be: @table @code @item 3 7th Edition (the default) @item 4 System III @item 5 System V @end table An optional second argument @var{release} to @code{AT} specifies the release number (such as ``System V Release 3''). @endDefmac @Defmac {UC, [@Var{version}], man} @cindex @code{man}macros, BSD compatibility Alters the footer for use with @acronym{BSD} manpages. This command exists only for compatibility; don't use it. The argument can be: @table @code @item 3 3rd Berkeley Distribution (the default) @item 4 4th Berkeley Distribution @item 5 4.2 Berkeley Distribution @item 6 4.3 Berkeley Distribution @item 7 4.4 Berkeley Distribution @end table @endDefmac @c --------------------------------------------------------------------- @node Predefined man strings, Preprocessors in man pages, Miscellaneous man macros, man @subsection Predefined strings The following strings are defined: @Defstr {S, man} Switch back to the default font size. @endDefstr @Defstr {HF, man} The typeface used for headings. The default is @samp{B}. @endDefstr @Defstr {R, man} The `registered' sign. @endDefstr @Defstr {Tm, man} The `trademark' sign. @endDefstr @DefstrList {lq, man} @DefstrListEnd {rq, man} @cindex @code{lq} glyph, and @code{lq} string [@code{man}] @cindex @code{rq} glyph, and @code{rq} string [@code{man}] Left and right quote. This is equal to @code{\(lq} and @code{\(rq}, respectively. @endDefstr @c --------------------------------------------------------------------- @node Preprocessors in man pages, Optional man extensions, Predefined man strings, man @subsection Preprocessors in @file{man} pages @cindex preprocessor, calling convention @cindex calling convention of preprocessors If a preprocessor like @code{gtbl} or @code{geqn} is needed, it has become common usage to make the first line of the man page look like this: @Example '\" @var{word} @endExample @pindex geqn@r{, invocation in manual pages} @pindex grefer@r{, invocation in manual pages} @pindex gtbl@r{, invocation in manual pages} @pindex man@r{, invocation of preprocessors} @noindent Note the single space character after the double quote. @var{word} consists of letters for the needed preprocessors: @samp{e} for @code{geqn}, @samp{r} for @code{grefer}, @samp{t} for @code{gtbl}. Modern implementations of the @code{man} program read this first line and automatically call the right preprocessor(s). @c --------------------------------------------------------------------- @node Optional man extensions, , Preprocessors in man pages, man @subsection Optional @file{man} extensions @pindex man.local Use the file @file{man.local} for local extensions to the @code{man} macros or for style changes. @unnumberedsubsubsec Custom headers and footers @cindex @code{man} macros, custom headers and footers In groff versions 1.18.2 and later, you can specify custom headers and footers by redefining the following macros in @file{man.local}. @Defmac {PT, , man} Control the content of the headers. Normally, the header prints the command name and section number on either side, and the optional fifth argument to @code{TH} in the center. @endDefmac @Defmac {BT, , man} Control the content of the footers. Normally, the footer prints the page number and the third and fourth arguments to @code{TH}. Use the @code{FT} number register to specify the footer position. The default is @minus{}0.5@dmn{i}. @endDefmac @unnumberedsubsubsec Ultrix-specific man macros @cindex Ultrix-specific @code{man} macros @cindex @code{man} macros, Ultrix-specific @pindex man.ultrix The @code{groff} source distribution includes a file named @file{man.ultrix}, containing macros compatible with the Ultrix variant of @code{man}. Copy this file into @file{man.local} (or use the @code{mso} request to load it) to enable the following macros. @Defmac {CT, @Var{key}, man} Print @samp{}. @endDefmac @Defmac {CW, , man} Print subsequent text using the constant width (Courier) typeface. @endDefmac @Defmac {Ds, , man} Begin a non-filled display. @endDefmac @Defmac {De, , man} End a non-filled display started with @code{Ds}. @endDefmac @Defmac {EX, [@Var{indent}], man} Begins a non-filled display using the constant width (Courier) typeface. Use the optional @var{indent} argument to indent the display. @endDefmac @Defmac {EE, , man} End a non-filled display started with @code{EX}. @endDefmac @Defmac {G, [@Var{text}], man} Sets @var{text} in Helvetica. If no text is present on the line where the macro is called, then the text of the next line appears in Helvetica. @endDefmac @Defmac {GL, [@Var{text}], man} Sets @var{text} in Helvetica Oblique. If no text is present on the line where the macro is called, then the text of the next line appears in Helvetica Oblique. @endDefmac @Defmac {HB, [@Var{text}], man} Sets @var{text} in Helvetica Bold. If no text is present on the line where the macro is called, then all text up to the next @code{HB} appears in Helvetica Bold. @endDefmac @Defmac {TB, [@Var{text}], man} Identical to @code{HB}. @endDefmac @Defmac {MS, @Var{title} @Var{sect} [@Var{punct}], man} Set a manpage reference in Ultrix format. The @var{title} is in Courier instead of italic. Optional punctuation follows the section number without an intervening space. @endDefmac @Defmac {NT, [@code{C}] [@Var{title}], man} Begin a note. Print the optional @Var{title}, or the word ``Note'', centered on the page. Text following the macro makes up the body of the note, and is indented on both sides. If the first argument is @code{C}, the body of the note is printed centered (the second argument replaces the word ``Note'' if specified). @endDefmac @Defmac {NE, , man} End a note begun with @code{NT}. @endDefmac @Defmac {PN, @Var{path} [@Var{punct}], man} Set the path name in constant width (Courier), followed by optional punctuation. @endDefmac @Defmac {Pn, [@Var{punct}] @Var{path} [@Var{punct}], man} When called with two arguments, identical to @code{PN}. When called with three arguments, set the second argument in constant width (Courier), bracketed by the first and third arguments in the current font. @endDefmac @Defmac {R, , man} Switch to roman font and turn off any underlining in effect. @endDefmac @Defmac {RN, , man} Print the string @samp{}. @endDefmac @Defmac {VS, [@code{4}], man} Start printing a change bar in the margin if the number @code{4} is specified. Otherwise, this macro does nothing. @endDefmac @Defmac {VE, , man} End printing the change bar begun by @code{VS}. @endDefmac @unnumberedsubsubsec Simple example The following example @file{man.local} file alters the @code{SH} macro to add some extra vertical space before printing the heading. Headings are printed in Helvetica Bold. @Example .\" Make the heading fonts Helvetica .ds HF HB . .\" Put more whitespace in front of headings. .rn SH SH-orig .de SH . if t .sp (u;\\n[PD]*2) . SH-orig \\$* .. @endExample @c ===================================================================== @node mdoc, ms, man, Macro Packages @section @file{mdoc} @cindex @code{mdoc} macros @c XXX documentation @c XXX this is a placeholder until we get stuff knocked into shape See the @cite{groff_mdoc(7)} man page (type @command{man groff_mdoc} at the command line). @c ===================================================================== @node ms, me, mdoc, Macro Packages @section @file{ms} @cindex @code{ms} macros The @file{-ms} macros are suitable for reports, letters, books, user manuals, and so forth. The package provides macros for cover pages, section headings, paragraphs, lists, footnotes, pagination, and a table of contents. @menu * ms Intro:: * General ms Structure:: * ms Document Control Registers:: * ms Cover Page Macros:: * ms Body Text:: * ms Page Layout:: * Differences from AT&T ms:: @end menu @c --------------------------------------------------------------------- @node ms Intro, General ms Structure, ms, ms @subsection Introduction to @file{ms} The original @file{-ms} macros were included with @acronym{AT&T} @code{troff} as well as the @file{man} macros. While the @file{man} package is intended for brief documents that can be read on-line as well as printed, the @file{ms} macros are suitable for longer documents that are meant to be printed rather than read on-line. The @file{ms} macro package included with @code{groff} is a complete, bottom-up re-implementation. Several macros (specific to @acronym{AT&T} or Berkeley) are not included, while several new commands are. @xref{Differences from AT&T ms}, for more information. @c --------------------------------------------------------------------- @node General ms Structure, ms Document Control Registers, ms Intro, ms @subsection General structure of an @file{ms} document @cindex @code{ms} macros, general structure The @file{ms} macro package expects a certain amount of structure, but not as much as packages such as @file{man} or @file{mdoc}. The simplest documents can begin with a paragraph macro (such as @code{LP} or @code{PP}), and consist of text separated by paragraph macros or even blank lines. Longer documents have a structure as follows: @table @strong @item Document type If you invoke the @code{RP} (report) macro on the first line of the document, @code{groff} prints the cover page information on its own page; otherwise it prints the information on the first page with your document text immediately following. Other document formats found in @acronym{AT&T} @code{troff} are specific to @acronym{AT&T} or Berkeley, and are not supported in @code{groff}. @item Format and layout By setting number registers, you can change your document's type (font and size), margins, spacing, headers and footers, and footnotes. @xref{ms Document Control Registers}, for more details. @item Cover page A cover page consists of a title, the author's name and institution, an abstract, and the date. @footnote{Actually, only the title is required.} @xref{ms Cover Page Macros}, for more details. @item Body Following the cover page is your document. You can use the @file{ms} macros to write reports, letters, books, and so forth. The package is designed for structured documents, consisting of paragraphs interspersed with headings and augmented by lists, footnotes, tables, and other common constructs. @xref{ms Body Text}, for more details. @item Table of contents Longer documents usually include a table of contents, which you can invoke by placing the @code{TC} macro at the end of your document. The @file{ms} macros have minimal indexing facilities, consisting of the @code{IX} macro, which prints an entry on standard error. Printing the table of contents at the end is necessary since @code{groff} is a single-pass text formatter, thus it cannot determine the page number of each section until that section has actually been set and printed. Since @file{ms} output is intended for hardcopy, you can manually relocate the pages containing the table of contents between the cover page and the body text after printing. @end table @c --------------------------------------------------------------------- @node ms Document Control Registers, ms Cover Page Macros, General ms Structure, ms @subsection Document control registers @cindex @code{ms} macros, document control registers The following is a list of document control number registers. For the sake of consistency, set registers related to margins at the beginning of your document, or just after the @code{RP} macro. You can set other registers later in your document, but you should keep them together at the beginning to make them easy to find and edit as necessary. @unnumberedsubsubsec Margin Settings @Defmpreg {PO, ms} Defines the page offset (i.e.@: the left margin). There is no explicit right margin setting; the combination of the @code{PO} and @code{LL} registers implicitly define the right margin width. Effective: next page. Default value: 1@dmn{i}. @endDefmpreg @Defmpreg {LL, ms} Defines the line length (i.e.@: the width of the body text). Effective: next paragraph. Default: 6@dmn{i}. @endDefmpreg @Defmpreg {LT, ms} Defines the title length (i.e.@: the header and footer width). This is usually the same as @code{LL}, but not necessarily. Effective: next paragraph. Default: 6@dmn{i}. @endDefmpreg @Defmpreg {HM, ms} Defines the header margin height at the top of the page. Effective: next page. Default: 1@dmn{i}. @endDefmpreg @Defmpreg {FM, ms} Defines the footer margin height at the bottom of the page. Effective: next page. Default: 1@dmn{i}. @endDefmpreg @unnumberedsubsubsec Text Settings @Defmpreg {PS, ms} Defines the point size of the body text. Effective: next paragraph. Default: 10@dmn{p}. @endDefmpreg @Defmpreg {VS, ms} Defines the space between lines (line height plus leading). Effective: next paragraph. Default: 12@dmn{p}. @endDefmpreg @unnumberedsubsubsec Paragraph Settings @Defmpreg {PI, ms} Defines the initial indent of a @code{.PP} paragraph. Effective: next paragraph. Default: 5@dmn{n}. @endDefmpreg @Defmpreg {PD, ms} Defines the space between paragraphs. Effective: next paragraph. Default: 0.3@dmn{v}. @endDefmpreg @Defmpreg {QI, ms} Defines the indent on both sides of a quoted (@code{.QP}) paragraph. Effective: next paragraph. Default: 5@dmn{n}. @endDefmpreg @unnumberedsubsubsec Footnote Settings @Defmpreg {FL, ms} Defines the length of a footnote. Effective: next footnote. Default: @math{@code{@\n[LL]} * 5 / 6}. @endDefmpreg @Defmpreg {FI, ms} Defines the footnote indent. Effective: next footnote. Default: 2@dmn{n}. @endDefmpreg @Defmpreg {FF, ms} The footnote format: @table @code @item 0 Prints the footnote number as a superscript; indents the footnote (default). @item 1 Prints the number followed by a period (like 1.) and indents the footnote. @item 2 Like 1, without an indent. @item 3 Like 1, but prints the footnote number as a hanging paragraph. @end table Effective: next footnote. Default: 0. @endDefmpreg @Defmpreg {FPS, ms} Defines the footnote point size. Effective: next footnote. Default: @math{@code{@\n[PS]} - 2}. @endDefmpreg @Defmpreg {FVS, ms} Defines the footnote vertical spacing. Effective: next footnote. Default: @math{@code{@\n[FPS]} + 2}. @endDefmpreg @Defmpreg {FPD, ms} Defines the footnote paragraph spacing. Effective: next footnote. Default: @math{@code{@\n[PD]} / 2}. @endDefmpreg @unnumberedsubsubsec Miscellaneous Number Registers @Defmpreg {MINGW, ms} Defines the minimum width between columns in a multi-column document. Effective: next page. Default: 2@dmn{n}. @endDefmpreg @c --------------------------------------------------------------------- @node ms Cover Page Macros, ms Body Text, ms Document Control Registers, ms @subsection Cover page macros @cindex @code{ms} macros, cover page @cindex cover page macros, [@code{ms}] Use the following macros to create a cover page for your document in the order shown. @Defmac {RP, [@code{no}], ms} Specifies the report format for your document. The report format creates a separate cover page. The default action (no @code{.RP} macro) is to print a subset of the cover page on page 1 of your document. If you use the word @code{no} as an optional argument, @code{groff} prints a title page but does not repeat any of the title page information (title, author, abstract, etc.) on page 1 of the document. @endDefmac @Defmac {DA, [@dots{}], ms} (optional) Print the current date, or the arguments to the macro if any, on the title page (if specified) and in the footers. This is the default for @code{nroff}. @endDefmac @Defmac {ND, [@dots{}], ms} (optional) Print the current date, or the arguments to the macro if any, on the title page (if specified) but not in the footers. This is the default for @code{troff}. @endDefmac @Defmac {TL, , ms} Specifies the document title. @code{groff} collects text following the @code{.TL} macro into the title, until reaching the author name or abstract. @endDefmac @Defmac {AU, , ms} Specifies the author's name, which appears on the line (or lines) immediately following. You can specify multiple authors as follows: @Example .AU John Doe .AI University of West Bumblefuzz .AU Martha Buck .AI Monolithic Corporation ... @endExample @endDefmac @Defmac {AI, , ms} Specifies the author's institution. You can specify multiple institutions in the same way that you specify multiple authors. @endDefmac @Defmac {AB, [@code{no}], ms} Begins the abstract. The default is to print the word @acronym{ABSTRACT}, centered and in italics, above the text of the abstract. The word @code{no} as an optional argument suppresses this heading. @endDefmac @Defmac {AE, , ms} End the abstract. @endDefmac The following is example mark-up for a title page. @cindex title page, example markup @cindex example markup, title page @Example @cartouche .RP .TL The Inevitability of Code Bloat in Commercial and Free Software .AU J. Random Luser .AI University of West Bumblefuzz .AB This report examines the long-term growth of the code bases in two large, popular software packages; the free Emacs and the commercial Microsoft Word. While differences appear in the type or order of features added, due to the different methodologies used, the results are the same in the end. .PP The free software approach is shown to be superior in that while free software can become as bloated as commercial offerings, free software tends to have fewer serious bugs and the added features are in line with user demand. .AE ... the rest of the paper follows ... @end cartouche @endExample @c --------------------------------------------------------------------- @node ms Body Text, ms Page Layout, ms Cover Page Macros, ms @subsection Body text @cindex @code{ms} macros, body text This section describes macros used to mark up the body of your document. Examples include paragraphs, sections, and other groups. @menu * Paragraphs in ms:: * Headings in ms:: * Highlighting in ms:: * Lists in ms:: * Indents in ms:: * Tabstops in ms:: * ms Displays and Keeps:: * ms Insertions:: * Example multi-page table:: * ms Footnotes:: @end menu @c --------------------------------------------------------------------- @node Paragraphs in ms, Headings in ms, ms Body Text, ms Body Text @subsubsection Paragraphs @cindex @code{ms} macros, paragraph handling The following paragraph types are available. @Defmac {PP, , ms} Sets a paragraph with an initial indent. @endDefmac @Defmac {LP, , ms} Sets a paragraph with no initial indent. @endDefmac @Defmac {QP, , ms} Sets a paragraph that is indented at both left and right margins. The effect is identical to the @acronym{HTML} @code{
} element. The next paragraph or heading returns margins to normal. @endDefmac @Defmac {XP, , ms} Sets a paragraph whose lines are indented, except for the first line. This is a Berkeley extension. @endDefmac The following markup uses all four paragraph macros. @Example @cartouche .NH 2 Cases used in the study .LP The following software and versions were considered for this report. .PP For commercial software, we chose .B "Microsoft Word for Windows" , starting with version 1.0 through the current version (Word 2000). .PP For free software, we chose .B Emacs , from its first appearance as a standalone editor through the current version (v20). See [Bloggs 2002] for details. .QP Franklin's Law applied to software: software expands to outgrow both RAM and disk space over time. .LP Bibliography: .XP Bloggs, Joseph R., .I "Everyone's a Critic" , Underground Press, March 2002. A definitive work that answers all questions and criticisms about the quality and usability of free software. @end cartouche @endExample @c --------------------------------------------------------------------- @node Headings in ms, Highlighting in ms, Paragraphs in ms, ms Body Text @subsubsection Headings @cindex @code{ms} macros, headings Use headings to create a hierarchical structure for your document. The @file{ms} macros print headings in @strong{bold}, using the same font family and point size as the body text. The following describes the heading macros: @DefmacList {NH, @Var{curr-level}, ms} @DefmacListEnd {NH, @t{S} @Var{level0} @dots{}, ms} Numbered heading. The argument is either a numeric argument to indicate the level of the heading, or the letter@tie{}@code{S} followed by numeric arguments to set the heading level explicitly. If you specify heading levels out of sequence, such as invoking @samp{.NH 3} after @samp{.NH 1}, @code{groff} prints a warning on standard error. @endDefmac @Defmac {SH, , ms} Unnumbered subheading. @endDefmac @c --------------------------------------------------------------------- @node Highlighting in ms, Lists in ms, Headings in ms, ms Body Text @subsubsection Highlighting @cindex @code{ms} macros, highlighting The @file{ms} macros provide a variety of methods to highlight or emphasize text: @Defmac {B, [@Var{txt} [@Var{post} [@Var{pre}]]], ms} Sets its first argument in @strong{bold type}. If you specify a second argument, @code{groff} prints it in the previous font after the bold text, with no intervening space (this allows you to set punctuation after the highlighted text without highlighting the punctuation). Similarly, it prints the third argument (if any) in the previous font @strong{before} the first argument. For example, @Example .B foo ) ( @endExample prints (@strong{foo}). If you give this macro no arguments, @code{groff} prints all text following in bold until the next highlighting, paragraph, or heading macro. @endDefmac @Defmac {R, [@Var{txt} [@Var{post} [@Var{pre}]]], ms} Sets its first argument in roman (or regular) type. It operates similarly to the @code{B}@tie{}macro otherwise. @endDefmac @Defmac {I, [@Var{txt} [@Var{post} [@Var{pre}]]], ms} Sets its first argument in @emph{italic type}. It operates similarly to the @code{B}@tie{}macro otherwise. @endDefmac @Defmac {CW, [@Var{txt} [@Var{post} [@Var{pre}]]], ms} Sets its first argument in a @code{constant width face}. It operates similarly to the @code{B}@tie{}macro otherwise. @endDefmac @Defmac {BI, [@Var{txt} [@Var{post} [@Var{pre}]]], ms} Sets its first argument in bold italic type. It operates similarly to the @code{B}@tie{}macro otherwise. @endDefmac @Defmac {BX, [@Var{txt}], ms} Prints its argument and draws a box around it. If you want to box a string that contains spaces, use a digit-width space (@code{\0}). @endDefmac @Defmac {UL, [@Var{txt} [@Var{post}]], ms} Prints its first argument with an underline. If you specify a second argument, @code{groff} prints it in the previous font after the underlined text, with no intervening space. @endDefmac @Defmac {LG, , ms} Prints all text following in larger type (two points larger than the current point size) until the next font size, highlighting, paragraph, or heading macro. You can specify this macro multiple times to enlarge the point size as needed. @endDefmac @Defmac {SM, , ms} Prints all text following in smaller type (two points smaller than the current point size) until the next type size, highlighting, paragraph, or heading macro. You can specify this macro multiple times to reduce the point size as needed. @endDefmac @Defmac {NL, , ms} Prints all text following in the normal point size (that is, the value of the @code{PS} register). @endDefmac @c --------------------------------------------------------------------- @node Lists in ms, Indents in ms, Highlighting in ms, ms Body Text @subsubsection Lists @cindex @code{ms} macros, lists The @code{.IP} macro handles duties for all lists. @Defmac {IP, [@Var{marker} [@Var{width}]], ms} The @var{marker} is usually a bullet glyph (@code{\[bu]}) for unordered lists, a number (or auto-incrementing number register) for numbered lists, or a word or phrase for indented (glossary-style) lists. The @var{width} specifies the indent for the body of each list item; its default unit is @samp{n}. Once specified, the indent remains the same for all list items in the document until specified again. @endDefmac The following is an example of a bulleted list. @cindex example markup, bulleted list [@code{ms}] @cindex bulleted list, example markup [@code{ms}] @Example A bulleted list: .IP \[bu] 2 lawyers .IP \[bu] guns .IP \[bu] money @endExample Produces: @Example A bulleted list: o lawyers o guns o money @endExample @sp 1 The following is an example of a numbered list. @cindex example markup, numbered list [@code{ms}] @cindex numbered list, example markup [@code{ms}] @Example .nr step 1 1 A numbered list: .IP \n[step] 3 lawyers .IP \n+[step] guns .IP \n+[step] money @endExample Produces: @Example A numbered list: 1. lawyers 2. guns 3. money @endExample Note the use of the auto-incrementing number register in this example. @sp 1 The following is an example of a glossary-style list. @cindex example markup, glossary-style list [@code{ms}] @cindex glossary-style list, example markup [@code{ms}] @Example A glossary-style list: .IP lawyers 0.4i Two or more attorneys. .IP guns Firearms, preferably large-caliber. .IP money Gotta pay for those lawyers and guns! @endExample Produces: @Example A glossary-style list: lawyers Two or more attorneys. guns Firearms, preferably large-caliber. money Gotta pay for those lawyers and guns! @endExample In the last example, the @code{IP} macro places the definition on the same line as the term if it has enough space; otherwise, it breaks to the next line and starts the definition below the term. This may or may not be the effect you want, especially if some of the definitions break and some do not. The following examples show two possible ways to force a break. The first workaround uses the @code{br} request to force a break after printing the term or label. @Example @cartouche A glossary-style list: .IP lawyers 0.4i Two or more attorneys. .IP guns .br Firearms, preferably large-caliber. .IP money Gotta pay for those lawyers and guns! @end cartouche @endExample @sp 1 The second workaround uses the @code{\p} escape to force the break. Note the space following the escape; this is important. If you omit the space, @code{groff} prints the first word on the same line as the term or label (if it fits) @strong{then} breaks the line. @Example @cartouche A glossary-style list: .IP lawyers 0.4i Two or more attorneys. .IP guns \p Firearms, preferably large-caliber. .IP money Gotta pay for those lawyers and guns! @end cartouche @endExample @sp 1 To set nested lists, use the @code{RS} and @code{RE} macros. @xref{Indents in ms}, for more information. @cindex @code{ms} macros, nested lists @cindex nested lists [@code{ms}] For example: @Example @cartouche .IP \[bu] 2 Lawyers: .RS .IP \[bu] Dewey, .IP \[bu] Cheatham, .IP \[bu] and Howe. .RE .IP \[bu] Guns @end cartouche @endExample Produces: @Example o Lawyers: o Dewey, o Cheatham, o and Howe. o Guns @endExample @c --------------------------------------------------------------------- @node Indents in ms, Tabstops in ms, Lists in ms, ms Body Text @subsubsection Indents In many situations, you may need to indent a section of text while still wrapping and filling. @xref{Lists in ms}, for an example of nested lists. @DefmacList {RS, , ms} @DefmacListEnd {RE, , ms} These macros begin and end an indented section. The @code{PI} register controls the amount of indent, allowing the indented text to line up under hanging and indented paragraphs. @endDefmac @xref{ms Displays and Keeps}, for macros to indent and turn off filling. @c --------------------------------------------------------------------- @node Tabstops in ms, ms Displays and Keeps, Indents in ms, ms Body Text @subsubsection Tab Stops Use the @code{ta} request to define tab stops as needed. @xref{Tabs and Fields}. @Defmac{TA, , ms} Use this macro to reset the tab stops to the default for @file{ms} (every 5n). You can redefine the @code{TA} macro to create a different set of default tab stops. @endDefmac @c --------------------------------------------------------------------- @node ms Displays and Keeps, ms Insertions, Tabstops in ms, ms Body Text @subsubsection Displays and keeps @cindex @code{ms} macros, displays @cindex @code{ms} macros, keeps @cindex keeps [@code{ms}] @cindex displays [@code{ms}] Use displays to show text-based examples or figures (such as code listings). Displays turn off filling, so lines of code are displayed as-is without inserting @code{br} requests in between each line. Displays can be @dfn{kept} on a single page, or allowed to break across pages. @DefmacList {DS, @t{L}, ms} @DefmacItem {LD, , ms} @DefmacListEnd {DE, , ms} Left-justified display. The @samp{.DS L} call generates a page break, if necessary, to keep the entire display on one page. The @code{LD} macro allows the display to break across pages. The @code{DE} macro ends the display. @endDefmac @DefmacList {DS, @t{I}, ms} @DefmacItem {ID, , ms} @DefmacListEnd {DE, , ms} Indents the display as defined by the @code{DI} register. The @samp{.DS I} call generates a page break, if necessary, to keep the entire display on one page. The @code{ID} macro allows the display to break across pages. The @code{DE} macro ends the display. @endDefmac @DefmacList {DS, @t{B}, ms} @DefmacItem {BD, , ms} @DefmacListEnd {DE, , ms} Sets a block-centered display: the entire display is left-justified, but indented so that the longest line in the display is centered on the page. The @samp{.DS B} call generates a page break, if necessary, to keep the entire display on one page. The @code{BD} macro allows the display to break across pages. The @code{DE} macro ends the display. @endDefmac @DefmacList {DS, @t{C}, ms} @DefmacItem {CD, , ms} @DefmacListEnd {DE, , ms} Sets a centered display: each line in the display is centered. The @samp{.DS C} call generates a page break, if necessary, to keep the entire display on one page. The @code{CD} macro allows the display to break across pages. The @code{DE} macro ends the display. @endDefmac @DefmacList {DS, @t{R}, ms} @DefmacItem {RD, , ms} @DefmacListEnd {DE, , ms} Right-justifies each line in the display. The @samp{.DS R} call generates a page break, if necessary, to keep the entire display on one page. The @code{RD} macro allows the display to break across pages. The @code{DE} macro ends the display. @endDefmac @DefmacList {Ds, , ms} @DefmacListEnd {De, , ms} These two macros are aliases for @code{DS} and @code{DE}, respectively. @endDefmac @sp 1 On occasion, you may want to @dfn{keep} other text together on a page. For example, you may want to keep two paragraphs together, or a paragraph that refers to a table (or list, or other item) immediately following. The @file{ms} macros provide the @code{KS} and @code{KE} macros for this purpose. @DefmacList {KS, , ms} @DefmacListEnd {KE, , ms} The @code{KS} macro begins a block of text to be kept on a single page, and the @code{KE} macro ends the block. @endDefmac @DefmacList {KF, , ms} @DefmacListEnd {KE, , ms} Specifies a @dfn{floating keep}; if the keep cannot fit on the current page, @code{groff} holds the contents of the keep and allows text following the keep (in the source file) to fill in the remainder of the current page. When the page breaks, whether by an explicit @code{bp} request or by reaching the end of the page, @code{groff} prints the floating keep at the top of the new page. This is useful for printing large graphics or tables that do not need to appear exactly where specified. @endDefmac You can also use the @code{ne} request to force a page break if there is not enough vertical space remaining on the page. @sp 1 Use the following macros to draw a box around a section of text (such as a display). @DefmacList {B1, , ms} @DefmacListEnd {B2, , ms} Marks the beginning and ending of text that is to have a box drawn around it. The @code{B1} macro begins the box; the @code{B2} macro ends it. Text in the box is automatically placed in a diversion (keep). @endDefmac @c --------------------------------------------------------------------- @node ms Insertions, Example multi-page table, ms Displays and Keeps, ms Body Text @subsubsection Tables, figures, equations, and references @cindex @code{ms} macros, tables @cindex @code{ms} macros, figures @cindex @code{ms} macros, equations @cindex @code{ms} macros, references @cindex tables [@code{ms}] @cindex figures [@code{ms}] @cindex equations [@code{ms}] @cindex references [@code{ms}] The @file{ms} macros support the standard @code{groff} preprocessors: @code{tbl}, @code{pic}, @code{eqn}, and @code{refer}. @pindex tbl @pindex pic @pindex eqn @pindex refer You mark text meant for preprocessors by enclosing it in pairs of tags as follows. @DefmacList {TS, [@code{H}], ms} @DefmacListEnd {TE, , ms} Denotes a table, to be processed by the @code{tbl} preprocessor. The optional argument@tie{}@code{H} to @code{TS} instructs @code{groff} to create a running header with the information up to the @code{TH} macro. @code{groff} prints the header at the beginning of the table; if the table runs onto another page, @code{groff} prints the header on the next page as well. @endDefmac @DefmacList {PS, , ms} @DefmacListEnd {PE, , ms} Denotes a graphic, to be processed by the @code{pic} preprocessor. You can create a @code{pic} file by hand, using the @acronym{AT&T} @code{pic} manual available on the Web as a reference, or by using a graphics program such as @code{xfig}. @endDefmac @DefmacList {EQ, [@Var{align}], ms} @DefmacListEnd {EN, , ms} Denotes an equation, to be processed by the @code{eqn} preprocessor. The optional @var{align} argument can be @code{C}, @code{L}, or@tie{}@code{I} to center (the default), left-justify, or indent the equation. @endDefmac @DefmacList {[, , ms} @DefmacListEnd {], , ms} Denotes a reference, to be processed by the @code{refer} preprocessor. The @acronym{GNU} @cite{refer(1)} man page provides a comprehensive reference to the preprocessor and the format of the bibliographic database. @endDefmac @menu * Example multi-page table:: @end menu @c --------------------------------------------------------------------- @node Example multi-page table, ms Footnotes, ms Insertions, ms Body Text @subsubsection An example multi-page table @cindex example markup, multi-page table [@code{ms}] @cindex multi-page table, example markup [@code{ms}] The following is an example of how to set up a table that may print across two or more pages. @Example @cartouche .TS H allbox expand; cb | cb . Text ...of heading... _ .TH .T& l | l . ... the rest of the table follows... .CW .TE @end cartouche @endExample @c --------------------------------------------------------------------- @node ms Footnotes, , Example multi-page table, ms Body Text @subsubsection Footnotes @cindex @code{ms} macros, footnotes @cindex footnotes [@code{ms}] The @file{ms} macro package has a flexible footnote system. You can specify either numbered footnotes or symbolic footnotes (that is, using a marker such as a dagger symbol). @Defstr {*, ms} Specifies the location of a numbered footnote marker in the text. @endDefesc @DefmacList {FS, , ms} @DefmacListEnd {FE, , ms} Specifies the text of the footnote. The default action is to create a numbered footnote; you can create a symbolic footnote by specifying a @dfn{mark} glyph (such as @code{\[dg]} for the dagger glyph) in the body text and as an argument to the @code{FS} macro, followed by the text of the footnote and the @code{FE} macro. @endDefmac You can control how @code{groff} prints footnote numbers by changing the value of the @code{FF} register. @xref{ms Document Control Registers}. @c --------------------------------------------------------------------- @node ms Page Layout, Differences from AT&T ms, ms Body Text, ms @subsection Page layout @cindex @code{ms} macros, page layout @cindex page layout [@code{ms}] The default output from the @file{ms} macros provides a minimalist page layout: it prints a single column, with the page number centered at the top of each page. It prints no footers. You can change the layout by setting the proper number registers and strings. @menu * ms Headers and Footers:: * ms Margins:: * ms Multiple Columns:: * ms TOC:: * ms Strings and Special Characters:: @end menu @c --------------------------------------------------------------------- @node ms Headers and Footers, ms Margins, ms Page Layout, ms Page Layout @subsubsection Headers and footers @cindex @code{ms} macros, headers @cindex @code{ms} macros, footers @cindex headers [@code{ms}] @cindex footers [@code{ms}] For documents that do not distinguish between odd and even pages, set the following strings: @DefstrList {LH, ms} @DefstrItem {CH, ms} @DefstrListEnd {RH, ms} Sets the left, center, and right headers. @endDefstr @DefstrList {LF, ms} @DefstrItem {CF, ms} @DefstrListEnd {RF, ms} Sets the left, center, and right footers. @endDefstr @sp 1 For documents that need different information printed in the even and odd pages, use the following macros: @DefmacList {OH, @t{'}@Var{left}@t{'}@Var{center}@t{'}@Var{right}@t{'}, ms} @DefmacItem {EH, @t{'}@Var{left}@t{'}@Var{center}@t{'}@Var{right}@t{'}, ms} @DefmacItem {OF, @t{'}@Var{left}@t{'}@Var{center}@t{'}@Var{right}@t{'}, ms} @DefmacListEnd {EF, @t{'}@Var{left}@t{'}@Var{center}@t{'}@Var{right}@t{'}, ms} The @code{OH} and @code{EH} macros define headers for the odd and even pages; the @code{OF} and @code{EF} macros define footers for the odd and even pages. This is more flexible than defining the individual strings. You can replace the quote (@code{'}) marks with any character not appearing in the header or footer text. @endDefmac @c --------------------------------------------------------------------- @node ms Margins, ms Multiple Columns, ms Headers and Footers, ms Page Layout @subsubsection Margins @cindex @code{ms} macros, margins You control margins using a set of number registers. @xref{ms Document Control Registers}, for details. @c --------------------------------------------------------------------- @node ms Multiple Columns, ms TOC, ms Margins, ms Page Layout @subsubsection Multiple columns @cindex @code{ms} macros, multiple columns @cindex multiple columns [@code{ms}] The @file{ms} macros can set text in as many columns as will reasonably fit on the page. The following macros are available; all of them force a page break if a multi-column mode is already set. However, if the current mode is single-column, starting a multi-column mode does @strong{not} force a page break. @Defmac {1C, , ms} Single-column mode. @endDefmac @Defmac {2C, , ms} Two-column mode. @endDefmac @Defmac {MC, [@Var{width} [@Var{gutter}]], ms} Multi-column mode. If you specify no arguments, it is equivalent to the @code{2C} macro. Otherwise, @var{width} is the width of each column and @var{gutter} is the space between columns. The @code{MINGW} number register controls the default gutter width. @endDefmac @c --------------------------------------------------------------------- @node ms TOC, ms Strings and Special Characters, ms Multiple Columns, ms Page Layout @subsubsection Creating a table of contents @cindex @code{ms} macros, creating table of contents @cindex table of contents, creating [@code{ms}] The facilities in the @file{ms} macro package for creating a table of contents are semi-automated at best. Assuming that you want the table of contents to consist of the document's headings, you need to repeat those headings wrapped in @code{XS} and @code{XE} macros. @DefmacList {XS, [@Var{page}], ms} @DefmacItem {XA, [@Var{page}], ms} @DefmacListEnd {XE, , ms} These macros define a table of contents or an individual entry in the table of contents, depending on their use. The macros are very simple; they cannot indent a heading based on its level. The easiest way to work around this is to add tabs to the table of contents string. The following is an example: @Example @cartouche .NH 1 Introduction .XS Introduction .XE .LP ... .CW .NH 2 Methodology .XS Methodology .XE .LP ... @end cartouche @endExample You can manually create a table of contents by beginning with the @code{XS} macro for the first entry, specifying the page number for that entry as the argument to @code{XS}. Add subsequent entries using the @code{XA} macro, specifying the page number for that entry as the argument to @code{XA}. The following is an example: @Example @cartouche .XS 1 Introduction .XA 2 A Brief History of the Universe .XA 729 Details of Galactic Formation ... .XE @end cartouche @endExample @endDefmac @Defmac {TC, [@code{no}], ms} Prints the table of contents on a new page, setting the page number to@tie{}@strong{i} (Roman numeral one). You should usually place this macro at the end of the file, since @code{groff} is a single-pass formatter and can only print what has been collected up to the point that the @code{TC} macro appears. The optional argument @code{no} suppresses printing the title specified by the string register @code{TOC}. @endDefmac @Defmac{PX, [@code{no}], ms} Prints the table of contents on a new page, using the current page numbering sequence. Use this macro to print a manually-generated table of contents at the beginning of your document. The optional argument @code{no} suppresses printing the title specified by the string register @code{TOC}. @endDefmac The @cite{Groff and Friends HOWTO} includes a @code{sed} script that automatically inserts @code{XS} and @code{XE} macro entries after each heading in a document. Altering the @code{NH} macro to automatically build the table of contents is perhaps initially more difficult, but would save a great deal of time in the long run if you use @file{ms} regularly. @c --------------------------------------------------------------------- @node ms Strings and Special Characters, , ms TOC, ms Page Layout @subsubsection Strings and Special Characters @cindex @code{ms} macros, strings @cindex @code{ms} macros, special characters @cindex @code{ms} macros, accent marks @cindex accent marks [@code{ms}] @cindex special characters [@code{ms}] @cindex strings [@code{ms}] The @file{ms} macros provide the following predefined strings. You can change the string definitions to help in creating documents in languages other than English. @Defstr {REFERENCES, ms} Contains the string printed at the beginning of the references (bibliography) page. The default is @samp{References}. @endDefstr @Defstr {ABSTRACT, ms} Contains the string printed at the beginning of the abstract. The default is @samp{ABSTRACT}. @endDefstr @Defstr {TOC, ms} Contains the string printed at the beginning of the table of contents. @endDefstr @DefstrList {MONTH1, ms} @DefstrItem {MONTH2, ms} @DefstrItem {MONTH3, ms} @DefstrItem {MONTH4, ms} @DefstrItem {MONTH5, ms} @DefstrItem {MONTH6, ms} @DefstrItem {MONTH7, ms} @DefstrItem {MONTH8, ms} @DefstrItem {MONTH9, ms} @DefstrItem {MONTH10, ms} @DefstrItem {MONTH11, ms} @DefstrListEnd {MONTH12, ms} Prints the full name of the month in dates. The default is @samp{January}, @samp{February}, etc. @endDefstr The following special characters are available@footnote{For an explanation what special characters are see @ref{Special Characters}.}: @Defstr {-, ms} Prints an em dash. @endDefstr @DefstrList {*Q, ms} @DefstrListEnd {*U, ms} Prints typographer's quotes in troff, plain quotes in nroff. @code{*Q} is the left quote and @code{*U} is the right quote. @endDefstr Improved accent marks are available in the @file{ms} macros. @Defmac {AM, , ms} Specify this macro at the beginning of your document to enable extended accent marks and special characters. This is a Berkeley extension. To use the accent marks, place them @strong{after} the character being accented. @endDefmac The following accent marks are available after invoking the @code{AM} macro: @Defstr {\', ms} Acute accent. @endDefstr @Defstr {\`, ms} Grave accent. @endDefstr @Defstr {^, ms} Circumflex. @endDefstr @Defstr {\,, ms} Cedilla. @endDefstr @Defstr {~, ms} Tilde. @endDefstr @deffn String @t{\*[:]} @ifnotinfo @stindex : @r{[}ms@r{]} @end ifnotinfo @ifinfo @stindex \*[@r{}] @r{[}ms@r{]} @end ifinfo Umlaut. @end deffn @Defstr {v, ms} Hacek. @endDefstr @Defstr {_, ms} Macron (overbar). @endDefstr @Defstr {., ms} Underdot. @endDefstr @Defstr {o, ms} Ring above. @endDefstr The following are standalone characters available after invoking the @code{AM} macro: @Defstr {?, ms} Upside-down question mark. @endDefstr @Defstr {!, ms} Upside-down exclamation point. @endDefstr @Defstr {8, ms} German @ss{} ligature. @endDefstr @Defstr {3, ms} Yogh. @endDefstr @Defstr {Th, ms} Uppercase thorn. @endDefstr @Defstr {th, ms} Lowercase thorn. @endDefstr @Defstr {D-, ms} Uppercase eth. @endDefstr @Defstr {d-, ms} Lowercase eth. @endDefstr @Defstr {q, ms} Hooked o. @endDefstr @Defstr {ae, ms} Lowercase @ae{} ligature. @endDefstr @Defstr {Ae, ms} Uppercase @AE{} ligature. @endDefstr @c --------------------------------------------------------------------- @node Differences from AT&T ms, , ms Page Layout, ms @subsection Differences from @acronym{AT&T} @file{ms} @cindex @code{ms} macros, differences from @acronym{AT&T} @cindex @acronym{AT&T} @code{troff}, @code{ms} macro package differences This section lists the (minor) differences between the @code{groff -ms} macros and @acronym{AT&T} @code{troff -ms} macros. @menu * Missing ms Macros:: * Additional ms Macros:: @end menu @c --------------------------------------------------------------------- @node Missing ms Macros, Additional ms Macros, Differences from AT&T ms, Differences from AT&T ms @subsubsection @code{troff} macros not appearing in @code{groff} Macros missing from @code{groff -ms} are cover page macros specific to Bell Labs. The macros known to be missing are: @table @code @item .TM Technical memorandum; a cover sheet style @item .IM Internal memorandum; a cover sheet style @item .MR Memo for record; a cover sheet style @item .MF Memo for file; a cover sheet style @item .EG Engineer's notes; a cover sheet style @item .TR Computing Science Tech Report; a cover sheet style @item .OK Other keywords @item .CS Cover sheet information @item .MH A cover sheet macro @end table @c --------------------------------------------------------------------- @node Additional ms Macros, , Missing ms Macros, Differences from AT&T ms @subsubsection @code{groff} macros not appearing in @acronym{AT&T} @code{troff} The @code{groff -ms} macros have a few minor extensions compared to the @acronym{AT&T} @code{troff -ms} macros. @Defmac {AM, , ms} Improved accent marks. @xref{ms Strings and Special Characters}, for details. @endDefmac @Defmac {DS, @t{I}, ms} Indented display. The default behavior of @acronym{AT&T} @code{troff -ms} was to indent; the @code{groff} default prints displays flush left with the body text. @endDefmac @Defmac {CW, , ms} Print text in @code{constant width} (Courier) font. @endDefmac @Defmac {IX, , ms} Indexing term (printed on standard error). You can write a script to capture and process an index generated in this manner. @endDefmac @sp 1 The following additional number registers appear in @code{groff -ms}: @Defmpreg {MINGW, ms} Specifies a minimum space between columns (for multi-column output); this takes the place of the @code{GW} register that was documented but apparently not implemented in @acronym{AT&T} @code{troff}. @endDefmpreg @sp 1 Several new string registers are available as well. You can change these to handle (for example) the local language. @xref{ms Strings and Special Characters}, for details. @c ===================================================================== @node me, mm, ms, Macro Packages @section @file{me} @cindex @code{me} macro package @c XXX documentation @c XXX this is a placeholder until we get stuff knocked into shape See the @file{meintro.me} and @file{meref.me} documents in groff's @file{doc} directory. @c ===================================================================== @node mm, , me, Macro Packages @section @file{mm} @cindex @code{mm} macro package @c XXX documentation @c XXX this is a placeholder until we get stuff knocked into shape See the @cite{groff_mm(7)} man page (type @command{man groff_mm} at the command line). @c ===================================================================== @c ===================================================================== @node gtroff Reference, Preprocessors, Macro Packages, Top @chapter @code{gtroff} Reference @cindex reference, @code{gtroff} @cindex @code{gtroff}, reference This chapter covers @strong{all} of the facilities of @code{gtroff}. Users of macro packages may skip it if not interested in details. @menu * Text:: * Measurements:: * Expressions:: * Identifiers:: * Embedded Commands:: * Registers:: * Manipulating Filling and Adjusting:: * Manipulating Hyphenation:: * Manipulating Spacing:: * Tabs and Fields:: * Character Translations:: * Troff and Nroff Mode:: * Line Layout:: * Line Control:: * Page Layout:: * Page Control:: * Fonts and Symbols:: * Sizes:: * Strings:: * Conditionals and Loops:: * Writing Macros:: * Page Motions:: * Drawing Requests:: * Traps:: * Diversions:: * Environments:: * Suppressing output:: * Colors:: * I/O:: * Postprocessor Access:: * Miscellaneous:: * Gtroff Internals:: * Debugging:: * Implementation Differences:: @end menu @c ===================================================================== @node Text, Measurements, gtroff Reference, gtroff Reference @section Text @cindex text, @code{gtroff} processing @code{gtroff} input files contain text with control commands interspersed throughout. But, even without control codes, @code{gtroff} still does several things with the input text: @itemize @bullet @item filling and adjusting @item adding additional space after sentences @item hyphenating @item inserting implicit line breaks @end itemize @menu * Filling and Adjusting:: * Hyphenation:: * Sentences:: * Tab Stops:: * Implicit Line Breaks:: * Input Conventions:: * Input Encodings:: @end menu @c --------------------------------------------------------------------- @node Filling and Adjusting, Hyphenation, Text, Text @subsection Filling and Adjusting @cindex filling @cindex adjusting When @code{gtroff} reads text, it collects words from the input and fits as many of them together on one output line as it can. This is known as @dfn{filling}. @cindex leading spaces @cindex spaces, leading and trailing @cindex extra spaces @cindex trailing spaces Once @code{gtroff} has a @dfn{filled} line, it tries to @dfn{adjust} it. This means it widens the spacing between words until the text reaches the right margin (in the default adjustment mode). Extra spaces between words are preserved, but spaces at the end of lines are ignored. Spaces at the front of a line cause a @dfn{break} (breaks are explained in @ref{Implicit Line Breaks}). @xref{Manipulating Filling and Adjusting}. @c --------------------------------------------------------------------- @node Hyphenation, Sentences, Filling and Adjusting, Text @subsection Hyphenation @cindex hyphenation Since the odds are not great for finding a set of words, for every output line, which fit nicely on a line without inserting excessive amounts of space between words, @code{gtroff} hyphenates words so that it can justify lines without inserting too much space between words. It uses an internal hyphenation algorithm (a simplified version of the algorithm used within @TeX{}) to indicate which words can be hyphenated and how to do so. When a word is hyphenated, the first part of the word is added to the current filled line being output (with an attached hyphen), and the other portion is added to the next line to be filled. @xref{Manipulating Hyphenation}. @c --------------------------------------------------------------------- @node Sentences, Tab Stops, Hyphenation, Text @subsection Sentences @cindex sentences Although it is often debated, some typesetting rules say there should be different amounts of space after various punctuation marks. For example, the @cite{Chicago typsetting manual} says that a period at the end of a sentence should have twice as much space following it as would a comma or a period as part of an abbreviation. @c XXX exact citation of Chicago manual @cindex sentence space @cindex space between sentences @cindex french-spacing @code{gtroff} does this by flagging certain characters (normally @samp{!}, @samp{?}, and @samp{.}) as @dfn{end-of-sentence} characters. When @code{gtroff} encounters one of these characters at the end of a line, it appends a normal space followed by a @dfn{sentence space} in the formatted output. (This justifies one of the conventions mentioned in @ref{Input Conventions}.) @cindex transparent characters @cindex character, transparent @cindex @code{dg} glyph, at end of sentence @cindex @code{rq} glyph, at end of sentence @cindex @code{"}, at end of sentence @cindex @code{'}, at end of sentence @cindex @code{)}, at end of sentence @cindex @code{]}, at end of sentence @cindex @code{*}, at end of sentence In addition, the following characters and symbols are treated transparently while handling end-of-sentence characters: @samp{"}, @samp{'}, @samp{)}, @samp{]}, @samp{*}, @code{\[dg]}, and @code{\[rq]}. See the @code{cflags} request in @ref{Using Symbols}, for more details. @cindex @code{\&}, at end of sentence To prevent the insertion of extra space after an end-of-sentence character (at the end of a line), append @code{\&}. @c --------------------------------------------------------------------- @node Tab Stops, Implicit Line Breaks, Sentences, Text @subsection Tab Stops @cindex tab stops @cindex stops, tabulator @cindex tab character @cindex character, tabulator @cindex @acronym{EBCDIC} encoding @cindex encoding, @acronym{EBCDIC} @code{gtroff} translates @dfn{tabulator characters}, also called @dfn{tabs} (normally code point @acronym{ASCII} @code{0x09} or @acronym{EBCDIC} @code{0x05}), in the input into movements to the next tabulator stop. These tab stops are initially located every half inch across the page. Using this, simple tables can be made easily. However, it can often be deceptive as the appearance (and width) of the text on a terminal and the results from @code{gtroff} can vary greatly. Also, a possible sticking point is that lines beginning with tab characters are still filled, again producing unexpected results. For example, the following input @multitable {12345678} {12345678} {12345678} {12345678} @item @tab 1 @tab 2 @tab 3 @item @tab @tab 4 @tab 5 @end multitable @noindent produces @multitable {12345678} {12345678} {12345678} {12345678} {12345678} {12345678} {12345678} @item @tab 1 @tab 2 @tab 3 @tab @tab 4 @tab 5 @end multitable @xref{Tabs and Fields}. @c --------------------------------------------------------------------- @node Implicit Line Breaks, Input Conventions, Tab Stops, Text @subsection Implicit Line Breaks @cindex implicit line breaks @cindex implicit breaks of lines @cindex line, implicit breaks @cindex break, implicit @cindex line break An important concept in @code{gtroff} is the @dfn{break}. When a break occurs, @code{gtroff} outputs the partially filled line (unjustified), and resumes collecting and filling text on the next output line. @cindex blank line @cindex empty line @cindex line, blank @cindex blank line macro (@code{blm}) There are several ways to cause a break in @code{gtroff}. A blank line not only causes a break, but it also outputs a one-line vertical space (effectively a blank line). Note that this behaviour can be modified with the blank line macro request @code{blm}. @xref{Blank Line Traps}. @cindex fill mode @cindex mode, fill A line that begins with a space causes a break and the space is output at the beginning of the next line. Note that this space isn't adjusted, even in fill mode. The end of file also causes a break -- otherwise the last line of the document may vanish! Certain requests also cause breaks, implicitly or explicitly. This is discussed in @ref{Manipulating Filling and Adjusting}. @c --------------------------------------------------------------------- @node Input Conventions, Input Encodings, Implicit Line Breaks, Text @subsection Input Conventions @cindex input conventions @cindex conventions for input Since @code{gtroff} does filling automatically, it is traditional in @code{groff} not to try and type things in as nicely formatted paragraphs. These are some conventions commonly used when typing @code{gtroff} text: @itemize @bullet @item Break lines after punctuation, particularly at the end of a sentence and in other logical places. Keep separate phrases on lines by themselves, as entire phrases are often added or deleted when editing. @item Try to keep lines less than 40-60@tie{}characters, to allow space for inserting more text. @item Do not try to do any formatting in a @acronym{WYSIWYG} manner (i.e., don't try using spaces to get proper indentation). @end itemize @c --------------------------------------------------------------------- @node Input Encodings, , Input Conventions, Text @subsection Input Encodings Currently, the following input encodings are available. @table @asis @item cp1047 @cindex encoding, input, @acronym{EBCDIC} @cindex @acronym{EBCDIC}, input encoding @cindex input encoding, @acronym{EBCDIC} @cindex encoding, input, cp1047 @cindex cp1047, input encoding @cindex input encoding, cp1047 @cindex IBM cp1047 input encoding @pindex cp1047.tmac This input encoding works only on @acronym{EBCDIC} platforms (and vice versa, the other input encodings don't work with @acronym{EBCDIC}); the file @file{cp1047.tmac} is by default loaded at start-up. @item latin-1 @cindex encoding, input, @w{latin-1} (ISO @w{8859-1}) @cindex @w{latin-1} (ISO @w{8859-1}), input encoding @cindex ISO @w{8859-1} (@w{latin-1}), input encoding @cindex input encoding, @w{latin-1} (ISO @w{8859-1}) @pindex latin1.tmac This is the default input encoding on non-@acronym{EBCDIC} platforms; the file @file{latin1.tmac} is loaded at start-up. @item latin-2 @cindex encoding, input, @w{latin-2} (ISO @w{8859-2}) @cindex @w{latin-2} (ISO @w{8859-2}), input encoding @cindex ISO @w{8859-2} (@w{latin-2}), input encoding @cindex input encoding, @w{latin-2} (ISO @w{8859-2}) @pindex latin2.tmac To use this encoding, either say @w{@samp{.mso latin2.tmac}} at the very beginning of your document or use @samp{-mlatin2} as a command line argument for @code{groff}. @item latin-9 (latin-0) @cindex encoding, input, @w{latin-9} (@w{latin-0}, ISO @w{8859-15}) @cindex @w{latin-9} (@w{latin-0}, ISO @w{8859-15}), input encoding @cindex ISO @w{8859-15} (@w{latin-9}, @w{latin-0}), input encoding @cindex input encoding, @w{latin-9} (@w{latin-9}, ISO @w{8859-15}) @pindex latin9.tmac This encoding is intended (at least in Europe) to replace @w{latin-1} encoding. The main difference to @w{latin-1} is that @w{latin-9} contains the Euro character. To use this encoding, either say @w{@samp{.mso latin9.tmac}} at the very beginning of your document or use @samp{-mlatin9} as a command line argument for @code{groff}. @end table Note that it can happen that some input encoding characters are not available for a particular output device. For example, saying @Example groff -Tlatin1 -mlatin9 ... @endExample @noindent will fail if you use the Euro character in the input. Usually, this limitation is present only for devices which have a limited set of output glyphs (e.g.@: @option{-Tascii} and @option{-Tlatin1}); for other devices it is usually sufficient to install proper fonts which contain the necessary glyphs. @pindex freeeuro.pfa @pindex ec.tmac Due to the importance of the Euro glyph in Europe, the groff package now comes with a @sc{PostScript} font called @file{freeeuro.pfa} which provides various glyph shapes for the Euro. With other words, @w{latin-9} encoding is supported for the @option{-Tps} device out of the box (@w{latin-2} isn't). By its very nature, @option{-Tutf8} supports all input encodings; @option{-Tdvi} has support for both @w{latin-2} and @w{latin-9} if the command line @option{-mec} is used also to load the file @file{ec.tmac} (which flips to the EC fonts). @c ===================================================================== @node Measurements, Expressions, Text, gtroff Reference @section Measurements @cindex measurements @cindex units of measurement @cindex basic unit (@code{u}) @cindex machine unit (@code{u}) @cindex measurement unit @cindex @code{u} unit @cindex unit, @code{u} @code{gtroff} (like many other programs) requires numeric parameters to specify various measurements. Most numeric parameters@footnote{those that specify vertical or horizontal motion or a type size} may have a @dfn{measurement unit} attached. These units are specified as a single character which immediately follows the number or expression. Each of these units are understood, by @code{gtroff}, to be a multiple of its @dfn{basic unit}. So, whenever a different measurement unit is specified @code{gtroff} converts this into its @dfn{basic units}. This basic unit, represented by a @samp{u}, is a device dependent measurement which is quite small, ranging from 1/75@dmn{th} to 1/72000@dmn{th} of an inch. The values may be given as fractional numbers; however, fractional basic units are always rounded to integers. Some of the measurement units are completely independent of any of the current settings (e.g.@: type size) of @code{gtroff}. @table @code @item i @cindex inch unit (@code{i}) @cindex @code{i} unit @cindex unit, @code{i} Inches. An antiquated measurement unit still in use in certain backwards countries with incredibly low-cost computer equipment. One inch is equal to@tie{}2.54@dmn{cm}. @item c @cindex centimeter unit (@code{c}) @cindex @code{c} unit @cindex unit, @code{c} Centimeters. One centimeter is equal to@tie{}0.3937@dmn{in}. @item p @cindex point unit (@code{p}) @cindex @code{p} unit @cindex unit, @code{p} Points. This is a typesetter's measurement used for measure type size. It is 72@tie{}points to an inch. @item P @cindex pica unit (@code{P}) @cindex @code{P} unit @cindex unit, @code{P} Pica. Another typesetting measurement. 6@tie{}Picas to an inch (and 12@tie{}points to a pica). @item s @itemx z @cindex @code{s} unit @cindex unit, @code{s} @cindex @code{z} unit @cindex unit, @code{z} @xref{Fractional Type Sizes}, for a discussion of these units. @item f @cindex @code{f} unit @cindex unit, @code{f} Fractions. Value is 65536. @xref{Colors}, for usage. @end table The other measurements understood by @code{gtroff} depend on settings currently in effect in @code{gtroff}. These are very useful for specifying measurements which should look proper with any size of text. @table @code @item m @cindex em unit (@code{m}) @cindex @code{m} unit @cindex unit, @code{m} Ems. This unit is equal to the current font size in points. So called because it is @emph{approximately} the width of the letter@tie{}@samp{m} in the current font. @item n @cindex en unit (@code{n}) @cindex @code{n} unit @cindex unit, @code{n} Ens. In @code{groff}, this is half of an em. @item v @cindex vertical space unit (@code{v}) @cindex space, vertical, unit (@code{v}) @cindex @code{v} unit @cindex unit, @code{v} Vertical space. This is equivalent to the current line spacing. @xref{Sizes}, for more information about this. @item M @cindex @code{M} unit @cindex unit, @code{M} 100ths of an em. @end table @menu * Default Units:: @end menu @c --------------------------------------------------------------------- @node Default Units, , Measurements, Measurements @subsection Default Units @cindex default units @cindex units, default Many requests take a default unit. While this can be helpful at times, it can cause strange errors in some expressions. For example, the line length request expects em units. Here are several attempts to get a line length of 3.5@tie{}inches and their results: @Example 3.5i @result{} 3.5i 7/2 @result{} 0i 7/2i @result{} 0i (7 / 2)u @result{} 0i 7i/2 @result{} 0.1i 7i/2u @result{} 3.5i @endExample @noindent Everything is converted to basic units first. In the above example it is assumed that 1@dmn{i} equals@tie{}240@dmn{u}, and 1@dmn{m} equals@tie{}10@dmn{p} (thus 1@dmn{m} equals@tie{}33@dmn{u}). The value 7@dmn{i}/2 is first handled as 7@dmn{i}/2@dmn{m}, then converted to 1680@dmn{u}/66@dmn{u} which is 25@dmn{u}, and this is approximately 0.1@dmn{i}. As can be seen, a scaling indicator after a closing parenthesis is simply ignored. @cindex measurements, specifying safely Thus, the safest way to specify measurements is to always attach a scaling indicator. If you want to multiply or divide by a certain scalar value, use @samp{u} as the unit for that value. @c ===================================================================== @node Expressions, Identifiers, Measurements, gtroff Reference @section Expressions @cindex expressions @code{gtroff} has most arithmetic operators common to other languages: @itemize @bullet @item @cindex arithmetic operators @cindex operators, arithmetic @opindex + @opindex - @opindex / @opindex * @opindex % Arithmetic: @samp{+} (addition), @samp{-} (subtraction), @samp{/} (division), @samp{*} (multiplication), @samp{%} (modulo). @code{gtroff} only provides integer arithmetic. The internal type used for computing results is @samp{int}, which is usually a 32@dmn{bit} signed integer. @item @cindex comparison operators @cindex operators, comparison @opindex < @opindex > @opindex >= @opindex <= @opindex = @opindex == Comparison: @samp{<} (less than), @samp{>} (greater than), @samp{<=} (less than or equal), @samp{>=} (greater than or equal), @samp{=} (equal), @samp{==} (the same as @samp{=}). @item @cindex logical operators @cindex operators, logical @opindex & @ifnotinfo @opindex : @end ifnotinfo @ifinfo @opindex @r{} @end ifinfo Logical: @samp{&} (logical and), @samp{:} (logical or). @item @cindex unary operators @cindex operators, unary @opindex - @opindex + @opindex ! @cindex @code{if} request, and the @samp{!} operator @cindex @code{while} request, and the @samp{!} operator Unary operators: @samp{-} (negating, i.e.@: changing the sign), @samp{+} (just for completeness; does nothing in expressions), @samp{!} (logical not; this works only within @code{if} and @code{while} requests). See below for the use of unary operators in motion requests. @item @cindex extremum operators (@code{>?}, @code{?}, @code{? @opindex ?} (maximum), @samp{? \n[y]) @endExample @noindent The register@tie{}@code{z} now contains@tie{}5. @item @cindex scaling operator @cindex operator, scaling Scaling: @code{(@var{c};@var{e})}. Evaluate@tie{}@var{e} using@tie{}@var{c} as the default scaling indicator. If @var{c} is missing, ignore scaling indicators in the evaluation of@tie{}@var{e}. @end itemize @cindex parentheses @cindex order of evaluation in expressions @cindex expression, order of evaluation @opindex ( @opindex ) Parentheses may be used as in any other language. However, in @code{gtroff} they are necessary to ensure order of evaluation. @code{gtroff} has no operator precedence; expressions are evaluated left to right. This means that @code{gtroff} evaluates @samp{3+5*4} as if it were parenthesized like @samp{(3+5)*4}, not as @samp{3+(5*4)}, as might be expected. @cindex @code{+}, and page motion @cindex @code{-}, and page motion @cindex motion operators @cindex operators, motion For many requests which cause a motion on the page, the unary operators @samp{+} and @samp{-} work differently if leading an expression. They then indicate a motion relative to the current position (down or up, respectively). @cindex @code{|}, and page motion @cindex absolute position operator (@code{|}) @cindex position, absolute, operator (@code{|}) Similarly, a leading @samp{|} operator indicates an absolute position. For vertical movements, it specifies the distance from the top of the page; for horizontal movements, it gives the distance from the beginning of the @emph{input} line. @cindex @code{bp} request, using @code{+} and@tie{}@code{-} @cindex @code{in} request, using @code{+} and@tie{}@code{-} @cindex @code{ll} request, using @code{+} and@tie{}@code{-} @cindex @code{lt} request, using @code{+} and@tie{}@code{-} @cindex @code{nm} request, using @code{+} and@tie{}@code{-} @cindex @code{nr} request, using @code{+} and@tie{}@code{-} @cindex @code{pl} request, using @code{+} and@tie{}@code{-} @cindex @code{pn} request, using @code{+} and@tie{}@code{-} @cindex @code{po} request, using @code{+} and@tie{}@code{-} @cindex @code{ps} request, using @code{+} and@tie{}@code{-} @cindex @code{pvs} request, using @code{+} and@tie{}@code{-} @cindex @code{rt} request, using @code{+} and@tie{}@code{-} @cindex @code{ti} request, using @code{+} and@tie{}@code{-} @cindex @code{\H}, using @code{+} and@tie{}@code{-} @cindex @code{\R}, using @code{+} and@tie{}@code{-} @cindex @code{\s}, using @code{+} and@tie{}@code{-} @samp{+} and @samp{-} are also treated differently by the following requests and escapes: @code{bp}, @code{in}, @code{ll}, @code{lt}, @code{nm}, @code{nr}, @code{pl}, @code{pn}, @code{po}, @code{ps}, @code{pvs}, @code{rt}, @code{ti}, @code{\H}, @code{\R}, and @code{\s}. Here, leading plus and minus signs indicate increments and decrements. @xref{Setting Registers}, for some examples. @Defesc {\\B, ', anything, '} @cindex numeric expression, valid @cindex valid numeric expression Return@tie{}1 if @var{anything} is a valid numeric expression; or@tie{}0 if @var{anything} is empty or not a valid numeric expression. @endDefesc @cindex space characters, in expressions @cindex expressions, and space characters Due to the way arguments are parsed, spaces are not allowed in expressions, unless the entire expression is surrounded by parentheses. @xref{Request and Macro Arguments}, and @ref{Conditionals and Loops}. @c ===================================================================== @node Identifiers, Embedded Commands, Expressions, gtroff Reference @section Identifiers @cindex identifiers Like any other language, @code{gtroff} has rules for properly formed @dfn{identifiers}. In @code{gtroff}, an identifier can be made up of almost any printable character, with the exception of the following characters: @itemize @bullet @item @cindex whitespace characters @cindex newline character @cindex character, whitespace Whitespace characters (spaces, tabs, and newlines). @item @cindex character, backspace @cindex backspace character @cindex @acronym{EBCDIC} encoding of backspace Backspace (@acronym{ASCII}@tie{}@code{0x08} or @acronym{EBCDIC}@tie{}@code{0x16}) and character code @code{0x01}. @item @cindex invalid input characters @cindex input characters, invalid @cindex characters, invalid input @cindex Unicode The following input characters are invalid and are ignored if @code{groff} runs on a machine based on @acronym{ASCII}, causing a warning message of type @samp{input} (see @ref{Debugging}, for more details): @code{0x00}, @code{0x0B}, @code{0x0D}-@code{0x1F}, @code{0x80}-@code{0x9F}. And here are the invalid input characters if @code{groff} runs on an @acronym{EBCDIC} host: @code{0x00}, @code{0x08}, @code{0x09}, @code{0x0B}, @code{0x0D}-@code{0x14}, @code{0x17}-@code{0x1F}, @code{0x30}-@code{0x3F}. Currently, some of these reserved codepoints are used internally, thus making it non-trivial to extend @code{gtroff} to cover Unicode or other character sets and encodings which use characters of these ranges. Note that invalid characters are removed before parsing; an identifier @code{foo}, followed by an invalid character, followed by @code{bar} is treated as @code{foobar}. @end itemize For example, any of the following is valid. @Example br PP (l end-list @@_ @endExample @cindex @code{]}, as part of an identifier @noindent Note that identifiers longer than two characters with a closing bracket (@samp{]}) in its name can't be accessed with escape sequences which expect an identifier as a parameter. For example, @samp{\[foo]]} accesses the glyph @samp{foo}, followed by @samp{]}, whereas @samp{\C'foo]'} really asks for glyph @samp{foo]}. @cindex @code{refer}, and macro names starting with @code{[} or @code{]} @cindex @code{[}, macro names starting with, and @code{refer} @cindex @code{]}, macro names starting with, and @code{refer} @cindex macro names, starting with @code{[} or @code{]}, and @code{refer} To avoid problems with the @code{refer} preprocessor, macro names should not start with @samp{[} or @samp{]}. Due to backwards compatibility, everything after @samp{.[} and @samp{.]} is handled as a special argument to @code{refer}. For example, @samp{.[foo} makes @code{refer} to start a reference, using @samp{foo} as a parameter. @Defesc {\\A, ', ident, '} Test whether an identifier @var{ident} is valid in @code{gtroff}. It expands to the character@tie{}1 or@tie{}0 according to whether its argument (usually delimited by quotes) is or is not acceptable as the name of a string, macro, diversion, number register, environment, or font. It returns@tie{}0 if no argument is given. This is useful for looking up user input in some sort of associative table. @Example \A'end-list' @result{} 1 @endExample @endDefesc @xref{Escapes}, for details on parameter delimiting characters. Identifiers in @code{gtroff} can be any length, but, in some contexts, @code{gtroff} needs to be told where identifiers end and text begins (and in different ways depending on their length): @itemize @bullet @item Single character. @cindex @code{(}, starting a two-character identifier @item Two characters. Must be prefixed with @samp{(} in some situations. @cindex @code{[}, starting an identifier @cindex @code{]}, ending an identifier @item Arbitrary length (@code{gtroff} only). Must be bracketed with @samp{[} and@tie{}@samp{]} in some situations. Any length identifier can be put in brackets. @end itemize @cindex undefined identifiers @cindex identifiers, undefined Unlike many other programming languages, undefined identifiers are silently ignored or expanded to nothing. When @code{gtroff} finds an undefined identifier, it emits a warning, doing the following: @itemize @bullet @item If the identifier is a string, macro, or diversion, @code{gtroff} defines it as empty. @item If the identifier is a number register, @code{gtroff} defines it with a value of@tie{}0. @end itemize @xref{Warnings}., @ref{Interpolating Registers}, and @ref{Strings}. Note that macros, strings, and diversions share the same name space. @Example .de xxx . nop foo .. . .di xxx bar .br .di . .xxx @result{} bar @endExample @noindent As can be seen in the previous example, @code{gtroff} reuses the identifier @samp{xxx}, changing it from a macro to a diversion. No warning is emitted! The contents of the first macro definition is lost. @xref{Interpolating Registers}, and @ref{Strings}. @c ===================================================================== @node Embedded Commands, Registers, Identifiers, gtroff Reference @section Embedded Commands @cindex embedded commands @cindex commands, embedded Most documents need more functionality beyond filling, adjusting and implicit line breaking. In order to gain further functionality, @code{gtroff} allows commands to be embedded into the text, in two ways. The first is a @dfn{request} which takes up an entire line, and does some large-scale operation (e.g.@: break lines, start new pages). The other is an @dfn{escape} which can be usually embedded anywhere in the text; most requests can accept it even as an argument. Escapes generally do more minor operations like sub- and superscripts, print a symbol, etc. @menu * Requests:: * Macros:: * Escapes:: @end menu @c --------------------------------------------------------------------- @node Requests, Macros, Embedded Commands, Embedded Commands @subsection Requests @cindex requests @cindex control character (@code{.}) @cindex character, control (@code{.}) @cindex no-break control character (@code{'}) @cindex character, no-break control (@code{'}) @cindex control character, no-break (@code{'}) A request line begins with a control character, which is either a single quote (@samp{'}, the @dfn{no-break control character}) or a period (@samp{.}, the normal @dfn{control character}). These can be changed; see @ref{Character Translations}, for details. After this there may be optional tabs or spaces followed by an identifier which is the name of the request. This may be followed by any number of space-separated arguments (@emph{no} tabs here). @cindex structuring source code of documents or macro packages @cindex documents, structuring the source code @cindex macro packages, structuring the source code Since a control character followed by whitespace only is ignored, it is common practice to use this feature for structuring the source code of documents or macro packages. @Example .de foo . tm This is foo. .. . . .de bar . tm This is bar. .. @endExample @cindex blank line @cindex blank line macro (@code{blm}) Another possibility is to use the blank line macro request @code{blm} by assigning an empty macro to it. @Example .de do-nothing .. .blm do-nothing \" activate blank line macro .de foo . tm This is foo. .. .de bar . tm This is bar. .. .blm \" deactivate blank line macro @endExample @xref{Blank Line Traps}. @cindex zero width space character (@code{\&}) @cindex character, zero width space (@code{\&}) @cindex space character, zero width (@code{\&}) @cindex @code{\&}, escaping control characters To begin a line with a control character without it being interpreted, precede it with @code{\&}. This represents a zero width space, which means it does not affect the output. In most cases the period is used as a control character. Several requests cause a break implicitly; using the single quote control character prevents this. @menu * Request and Macro Arguments:: @end menu @node Request and Macro Arguments, , Requests, Requests @subsubsection Request and Macro Arguments @cindex request arguments @cindex macro arguments @cindex arguments to requests and macros Arguments to requests and macros are processed much like the shell: The line is split into arguments according to spaces.@footnote{Plan@tie{}9's @code{troff} implementation also allows tabs for argument separation -- @code{gtroff} intentionally doesn't support this.} @cindex spaces, in a macro argument An argument to a macro which is intended to contain spaces can either be enclosed in double quotes, or have the spaces @dfn{escaped} with backslashes. This is @emph{not} true for requests. Here are a few examples for a hypothetical macro @code{uh}: @Example .uh The Mouse Problem .uh "The Mouse Problem" .uh The\ Mouse\ Problem @endExample @cindex @code{\~}, difference to @code{\@key{SP}} @cindex @code{\@key{SP}}, difference to @code{\~} @noindent The first line is the @code{uh} macro being called with 3 arguments, @samp{The}, @samp{Mouse}, and @samp{Problem}. The latter two have the same effect of calling the @code{uh} macro with one argument, @samp{The Mouse Problem}.@footnote{The last solution, i.e., using escaped spaces, is ``classical'' in the sense that it can be found in most @code{troff} documents. Nevertheless, it is not optimal in all situations, since @w{@samp{\ }} inserts a fixed-width, non-breaking space character which can't stretch. @code{gtroff} provides a different command @code{\~} to insert a stretchable, non-breaking space.} @cindex @code{"}, in a macro argument @cindex double quote, in a macro argument A double quote which isn't preceded by a space doesn't start a macro argument. If not closing a string, it is printed literally. For example, @Example .xxx a" "b c" "de"fg" @endExample @noindent has the arguments @samp{a"}, @w{@samp{b c}}, @samp{de}, and @samp{fg"}. Don't rely on this obscure behaviour! There are two possibilities to get a double quote reliably. @itemize @bullet @item Enclose the whole argument with double quotes and use two consecutive double quotes to represent a single one. This traditional solution has the disadvantage that double quotes don't survive argument expansion again if called in compatibility mode (using the @option{-C} option of @code{groff}): @Example .de xx . tm xx: `\\$1' `\\$2' `\\$3' . . yy "\\$1" "\\$2" "\\$3" .. .de yy . tm yy: `\\$1' `\\$2' `\\$3' .. .xx A "test with ""quotes""" . @result{} xx: `A' `test with "quotes"' `.' @result{} yy: `A' `test with ' `quotes""' @endExample @noindent If not in compatibility mode, you get the expected result @Example xx: `A' `test with "quotes"' `.' yy: `A' `test with "quotes"' `.' @endExample @noindent since @code{gtroff} preserves the input level. @item Use the double quote glyph @code{\(dq}. This works with and without compatibility mode enabled since @code{gtroff} doesn't convert @code{\(dq} back to a double quote input character. Not that this method won't work with @acronym{UNIX} @code{troff} in general since the glyph `dq' isn't defined normally. @end itemize @cindex @code{ds} request, and double quotes Double quotes in the @code{ds} request are handled differently. @xref{Strings}, for more details. @c --------------------------------------------------------------------- @node Macros, Escapes, Requests, Embedded Commands @subsection Macros @cindex macros @code{gtroff} has a @dfn{macro} facility for defining a series of lines which can be invoked by name. They are called in the same manner as requests -- arguments also may be passed basically in the same manner. @xref{Writing Macros}, and @ref{Request and Macro Arguments}. @c --------------------------------------------------------------------- @node Escapes, , Macros, Embedded Commands @subsection Escapes @cindex escapes Escapes may occur anywhere in the input to @code{gtroff}. They usually begin with a backslash and are followed by a single character which indicates the function to be performed. The escape character can be changed; see @ref{Character Translations}. Escape sequences which require an identifier as a parameter accept three possible syntax forms. @itemize @bullet @item The next single character is the identifier. @cindex @code{(}, starting a two-character identifier @item If this single character is an opening parenthesis, take the following two characters as the identifier. Note that there is no closing parenthesis after the identifier. @cindex @code{[}, starting an identifier @cindex @code{]}, ending an identifier @item If this single character is an opening bracket, take all characters until a closing bracket as the identifier. @end itemize @noindent Examples: @Example \fB \n(XX \*[TeX] @endExample @cindex @code{'}, delimiting arguments @cindex argument delimiting characters @cindex characters, argument delimiting @cindex delimiting characters for arguments Other escapes may require several arguments and/or some special format. In such cases the argument is traditionally enclosed in single quotes (and quotes are always used in this manual for the definitions of escape sequences). The enclosed text is then processed according to what that escape expects. Example: @Example \l'1.5i\(bu' @endExample @cindex @code{\o}, possible quote characters @cindex @code{\b}, possible quote characters @cindex @code{\X}, possible quote characters Note that the quote character can be replaced with any other character which does not occur in the argument (even a newline or a space character) in the following escapes: @code{\o}, @code{\b}, and @code{\X}. This makes e.g. @Example A caf \o e\' in Paris @result{} A caf@'e in Paris @endExample @noindent possible, but it is better not to use this feature to avoid confusion. @cindex @code{\%}, used as delimiter @cindex @code{\@key{SP}}, used as delimiter @cindex @code{\|}, used as delimiter @cindex @code{\^}, used as delimiter @cindex @code{\@{}, used as delimiter @cindex @code{\@}}, used as delimiter @cindex @code{\'}, used as delimiter @cindex @code{\`}, used as delimiter @cindex @code{\-}, used as delimiter @cindex @code{\_}, used as delimiter @cindex @code{\!}, used as delimiter @cindex @code{\?}, used as delimiter @cindex @code{\@@}, used as delimiter @cindex @code{\)}, used as delimiter @cindex @code{\/}, used as delimiter @cindex @code{\,}, used as delimiter @cindex @code{\&}, used as delimiter @ifnotinfo @cindex @code{\:}, used as delimiter @end ifnotinfo @ifinfo @cindex @code{\@r{}}, used as delimiter @end ifinfo @cindex @code{\~}, used as delimiter @cindex @code{\0}, used as delimiter @cindex @code{\a}, used as delimiter @cindex @code{\c}, used as delimiter @cindex @code{\d}, used as delimiter @cindex @code{\e}, used as delimiter @cindex @code{\E}, used as delimiter @cindex @code{\p}, used as delimiter @cindex @code{\r}, used as delimiter @cindex @code{\t}, used as delimiter @cindex @code{\u}, used as delimiter The following escapes sequences (which are handled similarly to characters since they don't take a parameter) are also allowed as delimiters: @code{\%}, @w{@samp{\ }}, @code{\|}, @code{\^}, @code{\@{}, @code{\@}}, @code{\'}, @code{\`}, @code{\-}, @code{\_}, @code{\!}, @code{\?}, @code{\@@}, @code{\)}, @code{\/}, @code{\,}, @code{\&}, @code{\:}, @code{\~}, @code{\0}, @code{\a}, @code{\c}, @code{\d}, @code{\e}, @code{\E}, @code{\p}, @code{\r}, @code{\t}, and @code{\u}. Again, don't use these if possible. @cindex @code{\A}, allowed delimiters @cindex @code{\B}, allowed delimiters @cindex @code{\Z}, allowed delimiters @cindex @code{\C}, allowed delimiters @cindex @code{\w}, allowed delimiters No newline characters as delimiters are allowed in the following escapes: @code{\A}, @code{\B}, @code{\Z}, @code{\C}, and @code{\w}. @cindex @code{\D}, allowed delimiters @cindex @code{\h}, allowed delimiters @cindex @code{\H}, allowed delimiters @cindex @code{\l}, allowed delimiters @cindex @code{\L}, allowed delimiters @cindex @code{\N}, allowed delimiters @cindex @code{\R}, allowed delimiters @cindex @code{\s}, allowed delimiters @cindex @code{\S}, allowed delimiters @cindex @code{\v}, allowed delimiters @cindex @code{\x}, allowed delimiters Finally, the escapes @code{\D}, @code{\h}, @code{\H}, @code{\l}, @code{\L}, @code{\N}, @code{\R}, @code{\s}, @code{\S}, @code{\v}, and @code{\x} can't use the following characters as delimiters: @itemize @bullet @item @cindex numbers, and delimiters @cindex digits, and delimiters The digits @code{0}-@code{9}. @item @cindex operators, as delimiters @cindex @code{+}, as delimiter @cindex @code{-}, as delimiter @cindex @code{/}, as delimiter @cindex @code{*}, as delimiter @cindex @code{%}, as delimiter @cindex @code{<}, as delimiter @cindex @code{>}, as delimiter @cindex @code{=}, as delimiter @cindex @code{&}, as delimiter @ifnotinfo @cindex @code{:}, as delimiter @end ifnotinfo @ifinfo @cindex , as delimiter @end ifinfo @cindex @code{(}, as delimiter @cindex @code{)}, as delimiter @cindex @code{.}, as delimiter The (single-character) operators @samp{+-/*%<>=&:().}. @item @cindex space character @cindex character, space @cindex tab character @cindex character, tab @cindex newline character @cindex character, newline The space, tab, and newline characters. @item @cindex @code{\%}, used as delimiter @ifnotinfo @cindex @code{\:}, used as delimiter @end ifnotinfo @ifinfo @cindex @code{\@r{}}, used as delimiter @end ifinfo @cindex @code{\@{}, used as delimiter @cindex @code{\@}}, used as delimiter @cindex @code{\'}, used as delimiter @cindex @code{\`}, used as delimiter @cindex @code{\-}, used as delimiter @cindex @code{\_}, used as delimiter @cindex @code{\!}, used as delimiter @cindex @code{\@@}, used as delimiter @cindex @code{\/}, used as delimiter @cindex @code{\c}, used as delimiter @cindex @code{\e}, used as delimiter @cindex @code{\p}, used as delimiter All escape sequences except @code{\%}, @code{\:}, @code{\@{}, @code{\@}}, @code{\'}, @code{\`}, @code{\-}, @code{\_}, @code{\!}, @code{\@@}, @code{\/}, @code{\c}, @code{\e}, and @code{\p}. @end itemize @cindex printing backslash (@code{\\}, @code{\e}, @code{\E}, @code{\[rs]}) @cindex backslash, printing (@code{\\}, @code{\e}, @code{\E}, @code{\[rs]}) To have a backslash (actually, the current escape character) appear in the output several escapes are defined: @code{\\}, @code{\e} or @code{\E}. These are very similar, and only differ with respect to being used in macros or diversions. @xref{Character Translations}, for an exact description of those escapes. @xref{Implementation Differences}, @ref{Copy-in Mode}, and @ref{Diversions}, @ref{Identifiers}, for more information. @menu * Comments:: @end menu @node Comments, , Escapes, Escapes @subsubsection Comments @cindex comments Probably one of the most@footnote{Unfortunately, this is a lie. But hopefully future @code{gtroff} hackers will believe it @code{:-)}} common forms of escapes is the comment. @Defesc {\\", , , } Start a comment. Everything to the end of the input line is ignored. This may sound simple, but it can be tricky to keep the comments from interfering with the appearance of the final output. @cindex @code{ds}, @code{ds1} requests, and comments @cindex @code{as}, @code{as1} requests, and comments If the escape is to the right of some text or a request, that portion of the line is ignored, but the space leading up to it is noticed by @code{gtroff}. This only affects the @code{ds} and @code{as} request and its variants. @cindex tabs, before comments @cindex comments, lining up with tabs One possibly irritating idiosyncracy is that tabs must not be used to line up comments. Tabs are not treated as whitespace between the request and macro arguments. @cindex undefined request @cindex request, undefined A comment on a line by itself is treated as a blank line, because after eliminating the comment, that is all that remains: @Example Test \" comment Test @endExample @noindent produces @Example Test Test @endExample To avoid this, it is common to start the line with @code{.\"} which causes the line to be treated as an undefined request and thus ignored completely. @cindex @code{'}, as a comment Another commenting scheme seen sometimes is three consecutive single quotes (@code{'''}) at the beginning of a line. This works, but @code{gtroff} gives a warning about an undefined macro (namely @code{''}), which is harmless, but irritating. @endDefesc @Defesc {\\#, , , } To avoid all this, @code{gtroff} has a new comment mechanism using the @code{\#} escape. This escape works the same as @code{\"} except that the newline is also ignored: @Example Test \# comment Test @endExample @noindent produces @Example Test Test @endExample @noindent as expected. @endDefesc @Defreq {ig, [@Var{end}]} Ignore all input until @code{gtroff} encounters the macro named @code{.}@var{end} on a line by itself (or @code{..} if @var{end} is not specified). This is useful for commenting out large blocks of text: @Example text text text... .ig This is part of a large block of text that has been temporarily(?) commented out. We can restore it simply by removing the .ig request and the ".." at the end of the block. .. More text text text... @endExample @noindent produces @Example text text text@dots{} More text text text@dots{} @endExample @noindent Note that the commented-out block of text does not cause a break. The input is read in copy-mode; auto-incremented registers @emph{are} affected (@pxref{Auto-increment}). @endDefreq @c ===================================================================== @node Registers, Manipulating Filling and Adjusting, Embedded Commands, gtroff Reference @section Registers @cindex registers Numeric variables in @code{gtroff} are called @dfn{registers}. There are a number of built-in registers, supplying anything from the date to details of formatting parameters. @xref{Identifiers}, for details on register identifiers. @menu * Setting Registers:: * Interpolating Registers:: * Auto-increment:: * Assigning Formats:: * Built-in Registers:: @end menu @c --------------------------------------------------------------------- @node Setting Registers, Interpolating Registers, Registers, Registers @subsection Setting Registers @cindex setting registers (@code{nr}, @code{\R}) @cindex registers, setting (@code{nr}, @code{\R}) Define or set registers using the @code{nr} request or the @code{\R} escape. @DefreqList {nr, ident value} @DefescListEnd {\\R, ', ident value, '} Set number register @var{ident} to @var{value}. If @var{ident} doesn't exist, @code{gtroff} creates it. The argument to @code{\R} usually has to be enclosed in quotes. @xref{Escapes}, for details on parameter delimiting characters. The @code{\R} escape doesn't produce an input token in @code{gtroff}; with other words, it vanishes completely after @code{gtroff} has processed it. @endDefreq For example, the following two lines are equivalent: @Example .nr a (((17 + (3 * 4))) % 4) \R'a (((17 + (3 * 4))) % 4)' @result{} 1 @endExample Both @code{nr} and @code{\R} have two additional special forms to increment or decrement a register. @DefreqList {nr, ident @t{+}@Var{value}} @DefreqItem {nr, ident @t{-}@Var{value}} @DefescItem {\\R, ', ident @t{+}value, '} @DefescListEnd {\\R, ', ident @t{-}value, '} Increment (decrement) register @var{ident} by @var{value}. @Example .nr a 1 .nr a +1 \na @result{} 2 @endExample @cindex negating register values To assign the negated value of a register to another register, some care must be taken to get the desired result: @Example .nr a 7 .nr b 3 .nr a -\nb \na @result{} 4 .nr a (-\nb) \na @result{} -3 @endExample @noindent The surrounding parentheses prevent the interpretation of the minus sign as a decrementing operator. An alternative is to start the assignment with a @samp{0}: @Example .nr a 7 .nr b -3 .nr a \nb \na @result{} 4 .nr a 0\nb \na @result{} -3 @endExample @endDefreq @Defreq {rr, ident} @cindex removing number register (@code{rr}) @cindex number register, removing (@code{rr}) @cindex register, removing (@code{rr}) Remove number register @var{ident}. If @var{ident} doesn't exist, the request is ignored. @endDefreq @Defreq {rnn, ident1 ident2} @cindex renaming number register (@code{rnn}) @cindex number register, renaming (@code{rnn}) @cindex register, renaming (@code{rnn}) Rename number register @var{ident1} to @var{ident2}. If either @var{ident1} or @var{ident2} doesn't exist, the request is ignored. @endDefreq @Defreq {aln, ident1 ident2} @cindex alias, number register, creating (@code{aln}) @cindex creating alias, for number register (@code{aln}) @cindex number register, creating alias (@code{aln}) @cindex register, creating alias (@code{aln}) Create an alias @var{ident1} for a number register @var{ident2}. The new name and the old name are exactly equivalent. If @var{ident1} is undefined, a warning of type @samp{reg} is generated, and the request is ignored. @xref{Debugging}, for information about warnings. @endDefreq @c --------------------------------------------------------------------- @node Interpolating Registers, Auto-increment, Setting Registers, Registers @subsection Interpolating Registers @cindex interpolating registers (@code{\n}) @cindex registers, interpolating (@code{\n}) Numeric registers can be accessed via the @code{\n} escape. @DefescList {\\n, , i, } @DefescItem {\\n, @lparen{}, id, } @DefescListEnd {\\n, @lbrack{}, ident, @rbrack} @cindex nested assignments @cindex assignments, nested @cindex indirect assignments @cindex assignments, indirect Interpolate number register with name @var{ident} (one-character name@tie{}@var{i}, two-character name @var{id}). This means that the value of the register is expanded in-place while @code{gtroff} is parsing the input line. Nested assignments (also called indirect assignments) are possible. @Example .nr a 5 .nr as \na+\na \n(as @result{} 10 @endExample @Example .nr a1 5 .nr ab 6 .ds str b .ds num 1 \n[a\n[num]] @result{} 5 \n[a\*[str]] @result{} 6 @endExample @endDefesc @c --------------------------------------------------------------------- @node Auto-increment, Assigning Formats, Interpolating Registers, Registers @subsection Auto-increment @cindex auto-increment @cindex increment, automatic Number registers can also be auto-incremented and auto-decremented. The increment or decrement value can be specified with a third argument to the @code{nr} request or @code{\R} escape. @Defreq {nr, ident value incr} @cindex @code{\R}, difference to @code{nr} Set number register @var{ident} to @var{value}; the increment for auto-incrementing is set to @var{incr}. Note that the @code{\R} escape doesn't support this notation. @endDefreq To activate auto-incrementing, the escape @code{\n} has a special syntax form. @DefescList {\\n, +, i, } @DefescItem {\\n, -, i, } @DefescItem {\\n, @lparen{}+, id, } @DefescItem {\\n, @lparen{}-, id, } @DefescItem {\\n, +@lparen{}, id, } @DefescItem {\\n, -@lparen{}, id, } @DefescItem {\\n, @lbrack{}+, ident, @rbrack{}} @DefescItem {\\n, @lbrack{}-, ident, @rbrack{}} @DefescItem {\\n, +@lbrack{}, ident, @rbrack{}} @DefescListEnd {\\n, -@lbrack{}, ident, @rbrack{}} Before interpolating, increment or decrement @var{ident} (one-character name@tie{}@var{i}, two-character name @var{id}) by the auto-increment value as specified with the @code{nr} request (or the @code{\R} escape). If no auto-increment value has been specified, these syntax forms are identical to @code{\n}. @endDefesc For example, @Example .nr a 0 1 .nr xx 0 5 .nr foo 0 -2 \n+a, \n+a, \n+a, \n+a, \n+a .br \n-(xx, \n-(xx, \n-(xx, \n-(xx, \n-(xx .br \n+[foo], \n+[foo], \n+[foo], \n+[foo], \n+[foo] @endExample @noindent produces @Example 1, 2, 3, 4, 5 -5, -10, -15, -20, -25 -2, -4, -6, -8, -10 @endExample @cindex increment value without changing the register @cindex value, incrementing without changing the register To change the increment value without changing the value of a register (@var{a} in the example), the following can be used: @Example .nr a \na 10 @endExample @c --------------------------------------------------------------------- @node Assigning Formats, Built-in Registers, Auto-increment, Registers @subsection Assigning Formats @cindex assigning formats (@code{af}) @cindex formats, assigning (@code{af}) When a register is used in the text of an input file (as opposed to part of an expression), it is textually replaced (or interpolated) with a representation of that number. This output format can be changed to a variety of formats (numbers, Roman numerals, etc.). This is done using the @code{af} request. @Defreq {af, ident format} Change the output format of a number register. The first argument @var{ident} is the name of the number register to be changed, and the second argument @var{format} is the output format. The following output formats are available: @table @code @item 1 Decimal arabic numbers. This is the default format: 0, 1, 2, 3,@tie{}@enddots{} @item 0@dots{}0 Decimal numbers with as many digits as specified. So, @samp{00} would result in printing numbers as 01, 02, 03,@tie{}@enddots{} In fact, any digit instead of zero will do; @code{gtroff} only counts how many digits are specified. As a consequence, @code{af}'s default format @samp{1} could be specified as @samp{0} also (and exactly this is returned by the @code{\g} escape, see below). @item I @cindex Roman numerals @cindex numerals, Roman Upper-case Roman numerals: 0, I, II, III, IV,@tie{}@enddots{} @item i Lower-case Roman numerals: 0, i, ii, iii, iv,@tie{}@enddots{} @item A Upper-case letters: 0, A, B, C, @dots{},@tie{}Z, AA, AB,@tie{}@enddots{} @item a Lower-case letters: 0, a, b, c, @dots{},@tie{}z, aa, ab,@tie{}@enddots{} @end table Omitting the number register format causes a warning of type @samp{missing}. @xref{Debugging}, for more details. Specifying a nonexistent format causes an error. The following example produces @samp{10, X, j, 010}: @Example .nr a 10 .af a 1 \" the default format \na, .af a I \na, .af a a \na, .af a 001 \na @endExample @cindex Roman numerals, maximum and minimum @cindex maximum values of Roman numerals @cindex minimum values of Roman numerals The largest number representable for the @samp{i} and @samp{I} formats is 39999 (or @minus{}39999); @acronym{UNIX} @code{troff} uses @samp{z} and @samp{w} to represent 10000 and 5000 in Roman numerals, and so does @code{gtroff}. Currently, the correct glyphs of Roman numeral five thousand and Roman numeral ten thousand (Unicode code points @code{U+2182} and @code{U+2181}, respectively) are not available. If @var{ident} doesn't exist, it is created. @cindex read-only register, changing format @cindex changing format, and read-only registers Changing the output format of a read-only register causes an error. It is necessary to first copy the register's value to a writeable register, then apply the @code{af} request to this other register. @endDefreq @DefescList {\\g, , i, } @DefescItem {\\g, @lparen{}, id, } @DefescListEnd {\\g, @lbrack{}, ident, @rbrack{}} @cindex format of register (@code{\g}) @cindex register, format (@code{\g}) Return the current format of the specified register @var{ident} (one-character name@tie{}@var{i}, two-character name @var{id}). For example, @samp{\ga} after the previous example would produce the string @samp{000}. If the register hasn't been defined yet, nothing is returned. @endDefesc @c --------------------------------------------------------------------- @node Built-in Registers, , Assigning Formats, Registers @subsection Built-in Registers @cindex built-in registers @cindex registers, built-in The following lists some built-in registers which are not described elsewhere in this manual. Any register which begins with a @samp{.} is read-only. A complete listing of all built-in registers can be found in @ref{Register Index}. @table @code @item \n[.F] @cindex current input file name register (@code{.F}) @cindex input file name, current, register (@code{.F}) @vindex \n[.F] This string-valued register returns the current input file name. @item \n[.H] @cindex horizontal resolution register (@code{.H}) @cindex resolution, horizontal, register (@code{.H}) @vindex .H Horizontal resolution in basic units. @item \n[.U] @cindex safer mode @cindex mode, safer @cindex unsafe mode @cindex mode, unsafe If @code{gtroff} is called with the @option{-U} command line option, the number register @code{.U} is set to@tie{}1, and zero otherwise. @xref{Groff Options}. @item \n[.V] @cindex vertical resolution register (@code{.V}) @cindex resolution, vertical, register (@code{.V}) @vindex .V Vertical resolution in basic units. @item \n[seconds] @cindex seconds, current time (@code{seconds}) @cindex time, current, seconds (@code{seconds}) @cindex current time, seconds (@code{seconds}) @vindex seconds The number of seconds after the minute, normally in the range@tie{}0 to@tie{}59, but can be up to@tie{}61 to allow for leap seconds. Initialized at start-up of @code{gtroff}. @item \n[minutes] @cindex minutes, current time (@code{minutes}) @cindex time, current, minutes (@code{minutes}) @cindex current time, minutes (@code{minutes}) @vindex minutes The number of minutes after the hour, in the range@tie{}0 to@tie{}59. Initialized at start-up of @code{gtroff}. @item \n[hours] @cindex hours, current time (@code{hours}) @cindex time, current, hours (@code{hours}) @cindex current time, hours (@code{hours}) @vindex hours The number of hours past midnight, in the range@tie{}0 to@tie{}23. Initialized at start-up of @code{gtroff}. @item \n[dw] @cindex day of the week register (@code{dw}) @cindex date, day of the week register (@code{dw}) @vindex dw Day of the week (1-7). @item \n[dy] @cindex day of the month register (@code{dy}) @cindex date, day of the month register (@code{dy}) @vindex dy Day of the month (1-31). @item \n[mo] @cindex month of the year register (@code{mo}) @cindex date, month of the year register (@code{mo}) @vindex mo Current month (1-12). @item \n[year] @cindex date, year register (@code{year}, @code{yr}) @cindex year, current, register (@code{year}, @code{yr}) @vindex year The current year. @item \n[yr] @vindex \n[yr] The current year minus@tie{}1900. Unfortunately, the documentation of @acronym{UNIX} Version@tie{}7's @code{troff} had a year@tie{}2000 bug: It incorrectly claimed that @code{yr} contains the last two digits of the year. That claim has never been true of either @acronym{AT&T} @code{troff} or GNU @code{troff}. Old @code{troff} input that looks like this: @Example '\" The following line stopped working after 1999 This document was formatted in 19\n(yr. @endExample @noindent can be corrected as follows: @Example This document was formatted in \n[year]. @endExample @noindent or, to be portable to older @code{troff} versions, as follows: @Example .nr y4 1900+\n(yr This document was formatted in \n(y4. @endExample @item \n[.c] @vindex .c @itemx \n[c.] @vindex c. @cindex input line number register (@code{.c}, @code{c.}) @cindex line number, input, register (@code{.c}, @code{c.}) The current @emph{input} line number. Register @samp{.c} is read-only, whereas @samp{c.} (a @code{gtroff} extension) is writable also, affecting both @samp{.c} and @samp{c.}. @item \n[ln] @vindex ln @cindex output line number register (@code{ln}) @cindex line number, output, register (@code{ln}) The current @emph{output} line number after a call to the @code{nm} request to activate line numbering. @xref{Miscellaneous}, for more information about line numbering. @item \n[.x] @vindex .x @cindex major version number register (@code{.x}) @cindex version number, major, register (@code{.x}) The major version number. For example, if the version number is 1.03 then @code{.x} contains@tie{}@samp{1}. @item \n[.y] @vindex .y @cindex minor version number register (@code{.y}) @cindex version number, minor, register (@code{.y}) The minor version number. For example, if the version number is 1.03 then @code{.y} contains@tie{}@samp{03}. @item \n[.Y] @vindex .Y @cindex revision number register (@code{.Y}) The revision number of @code{groff}. @item \n[$$] @vindex $$ @cindex process ID of @code{gtroff} register (@code{$$}) @cindex @code{gtroff}, process ID register (@code{$$}) The process ID of @code{gtroff}. @item \n[.g] @vindex .g @cindex @code{gtroff}, identification register (@code{.g}) @cindex GNU-specific register (@code{.g}) Always@tie{}1. Macros should use this to determine whether they are running under GNU @code{troff}. @item \n[.A] @vindex .A @cindex @acronym{ASCII} approximation output register (@code{.A}) If the command line option @option{-a} is used to produce an @acronym{ASCII} approximation of the output, this is set to@tie{}1, zero otherwise. @xref{Groff Options}. @item \n[.P] @vindex .P This register is set to@tie{}1 (and to@tie{}0 otherwise) if the current page is actually being printed, i.e., if the @option{-o} option is being used to only print selected pages. @xref{Groff Options}, for more information. @item \n[.T] @vindex .T If @code{gtroff} is called with the @option{-T} command line option, the number register @code{.T} is set to@tie{}1, and zero otherwise. @xref{Groff Options}. @item \*[.T] @stindex .T @cindex output device name string register (@code{.T}) A single read-write string register which contains the current output device (for example, @samp{latin1} or @samp{ps}). This is the only string register defined by @code{gtroff}. @end table @c ===================================================================== @node Manipulating Filling and Adjusting, Manipulating Hyphenation, Registers, gtroff Reference @section Manipulating Filling and Adjusting @cindex manipulating filling and adjusting @cindex filling and adjusting, manipulating @cindex adjusting and filling, manipulating @cindex justifying text @cindex text, justifying @cindex break @cindex line break @cindex @code{bp} request, causing implicit linebreak @cindex @code{ce} request, causing implicit linebreak @cindex @code{cf} request, causing implicit linebreak @cindex @code{fi} request, causing implicit linebreak @cindex @code{fl} request, causing implicit linebreak @cindex @code{in} request, causing implicit linebreak @cindex @code{nf} request, causing implicit linebreak @cindex @code{rj} request, causing implicit linebreak @cindex @code{sp} request, causing implicit linebreak @cindex @code{ti} request, causing implicit linebreak @cindex @code{trf} request, causing implicit linebreak Various ways of causing @dfn{breaks} were given in @ref{Implicit Line Breaks}. The @code{br} request likewise causes a break. Several other requests also cause breaks, but implicitly. These are @code{bp}, @code{ce}, @code{cf}, @code{fi}, @code{fl}, @code{in}, @code{nf}, @code{rj}, @code{sp}, @code{ti}, and @code{trf}. @Defreq {br, } Break the current line, i.e., the input collected so far is emitted without adjustment. If the no-break control character is used, @code{gtroff} suppresses the break: @Example a 'br b @result{} a b @endExample @endDefreq Initially, @code{gtroff} fills and adjusts text to both margins. Filling can be disabled via the @code{nf} request and re-enabled with the @code{fi} request. @DefreqList {fi, } @DefregListEnd {.u} @cindex fill mode (@code{fi}) @cindex mode, fill (@code{fi}) Activate fill mode (which is the default). This request implicitly enables adjusting; it also inserts a break in the text currently being filled. The read-only number register @code{.u} is set to@tie{}1. The fill mode status is associated with the current environment (@pxref{Environments}). See @ref{Line Control}, for interaction with the @code{\c} escape. @endDefreq @Defreq {nf, } @cindex no-fill mode (@code{nf}) @cindex mode, no-fill (@code{nf}) Activate no-fill mode. Input lines are output as-is, retaining line breaks and ignoring the current line length. This command implicitly disables adjusting; it also causes a break. The number register @code{.u} is set to@tie{}0. The fill mode status is associated with the current environment (@pxref{Environments}). See @ref{Line Control}, for interaction with the @code{\c} escape. @endDefreq @DefreqList {ad, [@Var{mode}]} @DefregListEnd {.j} Set adjusting mode. Activation and deactivation of adjusting is done implicitly with calls to the @code{fi} or @code{nf} requests. @var{mode} can have one of the following values: @table @code @item l @cindex ragged-right Adjust text to the left margin. This produces what is traditionally called ragged-right text. @item r @cindex ragged-left Adjust text to the right margin, producing ragged-left text. @item c @cindex centered text @cindex @code{ce} request, difference to @samp{.ad@tie{}c} Center filled text. This is different to the @code{ce} request which only centers text without filling. @item b @itemx n Justify to both margins. This is the default used by @code{gtroff}. @end table Finally, @var{mode} can be the numeric argument returned by the @code{.j} register. With no argument, @code{gtroff} adjusts lines in the same way it did before adjusting was deactivated (with a call to @code{na}, for example). @Example text .ad r .nr ad \n[.j] text .ad c text .na text .ad \" back to centering text .ad \n[ad] \" back to right justifying @endExample @cindex adjustment mode register (@code{.j}) The current adjustment mode is available in the read-only number register @code{.j}; it can be stored and subsequently used to set adjustment. The adjustment mode status is associated with the current environment (@pxref{Environments}). @endDefreq @Defreq {na, } Disable adjusting. This request won't change the current adjustment mode: A subsequent call to @code{ad} uses the previous adjustment setting. The adjustment mode status is associated with the current environment (@pxref{Environments}). @endDefreq @DefreqList {brp, } @DefescListEnd {\\p, , , } Adjust the current line and cause a break. In most cases this produces very ugly results since @code{gtroff} doesn't have a sophisticated paragraph building algorithm (as @TeX{} have, for example); instead, @code{gtroff} fills and adjusts a paragraph line by line: @Example This is an uninteresting sentence. This is an uninteresting sentence.\p This is an uninteresting sentence. @endExample @noindent is formatted as @Example This is an uninteresting sentence. This is an uninteresting sentence. This is an uninteresting sentence. @endExample @endDefreq @DefreqList {ss, word_space_size [@Var{sentence_space_size}]} @DefregItem {.ss} @DefregListEnd {.sss} @cindex word space size register (@code{.ss}) @cindex size of word space register (@code{.ss}) @cindex space between words register (@code{.ss}) @cindex sentence space size register (@code{.sss}) @cindex size of sentence space register (@code{.sss}) @cindex space between sentences register (@code{.sss}) Change the size of a space between words. It takes its units as one twelfth of the space width parameter for the current font. Initially both the @var{word_space_size} and @var{sentence_space_size} are@tie{}12. In fill mode, the values specify the minimum distance. @cindex fill mode @cindex mode, fill If two arguments are given to the @code{ss} request, the second argument sets the sentence space size. If the second argument is not given, sentence space size is set to @var{word_space_size}. The sentence space size is used in two circumstances: If the end of a sentence occurs at the end of a line in fill mode, then both an inter-word space and a sentence space are added; if two spaces follow the end of a sentence in the middle of a line, then the second space is a sentence space. If a second argument is never given to the @code{ss} request, the behaviour of @acronym{UNIX} @code{troff} is the same as that exhibited by GNU @code{troff}. In GNU @code{troff}, as in @acronym{UNIX} @code{troff}, a sentence should always be followed by either a newline or two spaces. The read-only number registers @code{.ss} and @code{.sss} hold the values of the parameters set by the first and second arguments of the @code{ss} request. The word space and sentence space values are associated with the current environment (@pxref{Environments}). Contrary to @acronym{AT&T} @code{troff}, this request is @emph{not} ignored if a TTY output device is used; the given values are then rounded down to a multiple of@tie{}12 (@pxref{Implementation Differences}). The request is ignored if there is no parameter. @cindex discardable horizontal space @cindex space, discardable, horizontal @cindex horizontal discardable space Another useful application of the @code{ss} request is to insert discardable horizontal space, i.e., space which is discarded at a line break. For example, paragraph-style footnotes could be separated this way: @Example .ll 4.5i 1.\ This is the first footnote.\c .ss 48 .nop .ss 12 2.\ This is the second footnote. @endExample @noindent The result: @Example 1. This is the first footnote. 2. This is the second footnote. @endExample @noindent Note that the @code{\h} escape produces unbreakable space. @endDefreq @DefreqList {ce, [@Var{nnn}]} @DefregListEnd {.ce} @cindex centering lines (@code{ce}) @cindex lines, centering (@code{ce}) Center text. While the @w{@samp{.ad c}} request also centers text, it fills the text as well. @code{ce} does not fill the text it affects. This request causes a break. The number of lines still to be centered is associated with the current environment (@pxref{Environments}). The following example demonstrates the differences. Here the input: @Example .ll 4i .ce 1000 This is a small text fragment which shows the differences between the `.ce' and the `.ad c' request. .ce 0 .ad c This is a small text fragment which shows the differences between the `.ce' and the `.ad c' request. @endExample @noindent And here the result: @Example This is a small text fragment which shows the differences between the `.ce' and the `.ad c' request. This is a small text fragment which shows the differences between the `.ce' and the `.ad c' request. @endExample With no arguments, @code{ce} centers the next line of text. @var{nnn} specifies the number of lines to be centered. If the argument is zero or negative, centering is disabled. The basic length for centering text is the line length (as set with the @code{ll} request) minus the indentation (as set with the @code{in} request). Temporary indentation is ignored. As can be seen in the previous example, it is a common idiom to turn on centering for a large number of lines, and to turn off centering after text to be centered. This is useful for any request which takes a number of lines as an argument. The @code{.ce} read-only number register contains the number of lines remaining to be centered, as set by the @code{ce} request. @endDefreq @DefreqList {rj, [@Var{nnn}]} @DefregListEnd {.rj} @cindex justifying text (@code{rj}) @cindex text, justifying (@code{rj}) @cindex right-justifying (@code{rj}) Justify unfilled text to the right margin. Arguments are identical to the @code{ce} request. The @code{.rj} read-only number register is the number of lines to be right-justified as set by the @code{rj} request. This request causes a break. The number of lines still to be right-justified is associated with the current environment (@pxref{Environments}). @endDefreq @c ===================================================================== @node Manipulating Hyphenation, Manipulating Spacing, Manipulating Filling and Adjusting, gtroff Reference @section Manipulating Hyphenation @cindex manipulating hyphenation @cindex hyphenation, manipulating As discussed in @ref{Hyphenation}, @code{gtroff} hyphenates words. There are a number of ways to influence hyphenation. @DefreqList {hy, [@Var{mode}]} @DefregListEnd {.hy} Enable hyphenation. The request has an optional numeric argument, @var{mode}, to restrict hyphenation if necessary: @table @code @item 1 The default argument if @var{mode} is omitted. Hyphenate without restrictions. This is also the start-up value of @code{gtroff}. @item 2 Do not hyphenate the last word on a page or column. @item 4 Do not hyphenate the last two characters of a word. @item 8 Do not hyphenate the first two characters of a word. @end table Values in the previous table are additive. For example, the value@tie{}12 causes @code{gtroff} to neither hyphenate the last two nor the first two characters of a word. @cindex hyphenation restrictions register (@code{.hy}) The current hyphenation restrictions can be found in the read-only number register @samp{.hy}. The hyphenation mode is associated with the current environment (@pxref{Environments}). @endDefreq @Defreq {nh, } Disable hyphenation (i.e., set the hyphenation mode to zero). Note that the hyphenation mode of the last call to @code{hy} is not remembered. The hyphenation mode is associated with the current environment (@pxref{Environments}). @endDefreq @DefreqList {hlm, [@Var{nnn}]} @DefregItem {.hlm} @DefregListEnd {.hlc} @cindex explicit hyphen (@code{\%}) @cindex hyphen, explicit (@code{\%}) @cindex consecutive hyphenated lines (@code{hlm}) @cindex lines, consecutive hyphenated (@code{hlm}) @cindex hyphenated lines, consecutive (@code{hlm}) Set the maximum number of consecutive hyphenated lines to @var{nnn}. If this number is negative, there is no maximum. The default value is@tie{}@minus{}1 if @var{nnn} is omitted. This value is associated with the current environment (@pxref{Environments}). Only lines output from a given environment count towards the maximum associated with that environment. Hyphens resulting from @code{\%} are counted; explicit hyphens are not. The current setting of @code{hlm} is available in the @code{.hlm} read-only number register. Also the number of immediately preceding consecutive hyphenated lines are available in the read-only number register @samp{.hlc}. @endDefreq @Defreq {hw, word1 word2 @dots{}} Define how @var{word1}, @var{word2}, etc.@: are to be hyphenated. The words must be given with hyphens at the hyphenation points. For example: @Example .hw in-sa-lub-rious @endExample @noindent Besides the space character, any character whose hyphenation code value is zero can be used to separate the arguments of @code{hw} (see the documentation for the @code{hcode} request below for more information). In addition, this request can be used more than once. Hyphenation exceptions specified with the @code{hw} request are associated with the current hyphenation language; it causes an error if there is no current hyphenation language. This request is ignored if there is no parameter. In old versions of @code{troff} there was a limited amount of space to store such information; fortunately, with @code{gtroff}, this is no longer a restriction. @endDefreq @DefescList {\\%, , , } @deffnx Escape @t{\:} @ifnotinfo @esindex \: @end ifnotinfo @ifinfo @esindex \@r{} @end ifinfo @cindex hyphenation character (@code{\%}) @cindex character, hyphenation (@code{\%}) @cindex disabling hyphenation (@code{\%}) @cindex hyphenation, disabling (@code{\%}) To tell @code{gtroff} how to hyphenate words on the fly, use the @code{\%} escape, also known as the @dfn{hyphenation character}. Preceding a word with this character prevents it from being hyphenated; putting it inside a word indicates to @code{gtroff} that the word may be hyphenated at that point. Note that this mechanism only affects that one occurrence of the word; to change the hyphenation of a word for the entire document, use the @code{hw} request. The @code{\:} escape inserts a zero-width break point (that is, the word breaks but without adding a hyphen). @Example ... check the /var/log/\:httpd/\:access_log file ... @endExample @cindex @code{\X}, followed by @code{\%} @cindex @code{\Y}, followed by @code{\%} @cindex @code{\%}, following @code{\X} or @code{\Y} Note that @code{\X} and @code{\Y} start a word, that is, the @code{\%} escape in (say) @w{@samp{\X'...'\%foobar}} and @w{@samp{\Y'...'\%foobar}} no longer prevents hyphenation but inserts a hyphenation point at the beginning of @samp{foobar}; most likely this isn't what you want to do. @endDefesc @Defreq {hc, [@Var{char}]} Change the hyphenation character to @var{char}. This character then works the same as the @code{\%} escape, and thus, no longer appears in the output. Without an argument, @code{hc} resets the hyphenation character to be @code{\%} (the default) only. The hyphenation character is associated with the current environment (@pxref{Environments}). @endDefreq @DefreqList {hpf, pattern_file} @DefreqItem {hpfa, pattern_file} @DefreqListEnd {hpfcode, a b [c d @dots{}]} @cindex hyphenation patterns (@code{hpf}) @cindex patterns for hyphenation (@code{hpf}) Read in a file of hyphenation patterns. This file is searched for in the same way as @file{@var{name}.tmac} (or @file{tmac.@var{name}}) is searched for if the @option{-m@var{name}} option is specified. It should have the same format as (simple) @TeX{} patterns files. More specifically, the following scanning rules are implemented. @itemize @bullet @item A percent sign starts a comment (up to the end of the line) even if preceded by a backslash. @item No support for `digraphs' like @code{\$}. @item @code{^^@var{xx}} (@var{x} is 0-9 or a-f) and @code{^^@var{x}} (character code of @var{x} in the range 0-127) are recognized; other use of @code{^} causes an error. @item No macro expansion. @item @code{hpf} checks for the expression @code{\patterns@{@dots{}@}} (possibly with whitespace before and after the braces). Everything between the braces is taken as hyphenation patterns. Consequently, @code{@{} and @code{@}} are not allowed in patterns. @item Similarly, @code{\hyphenation@{@dots{}@}} gives a list of hyphenation exceptions. @item @code{\endinput} is recognized also. @item For backwards compatibility, if @code{\patterns} is missing, the whole file is treated as a list of hyphenation patterns (only recognizing the @code{%} character as the start of a comment). @end itemize If no @code{hpf} request is specified (either in the document or in a macro package), @code{gtroff} won't hyphenate at all. The @code{hpfa} request appends a file of patterns to the current list. The @code{hpfcode} request defines mapping values for character codes in hyphenation patterns. @code{hpf} or @code{hpfa} then apply the mapping (after reading the patterns) before replacing or appending them to the current list of patterns. Its arguments are pairs of character codes -- integers from 0 to@tie{}255. The request maps character code@tie{}@var{a} to code@tie{}@var{b}, code@tie{}@var{c} to code@tie{}@var{d}, and so on. You can use character codes which would be invalid otherwise. @pindex troffrc @pindex troffrc-end @pindex hyphen.us @pindex hyphenex.us The set of hyphenation patterns is associated with the current language set by the @code{hla} request. The @code{hpf} request is usually invoked by the @file{troffrc} or @file{troffrc-end} file; by default, @file{troffrc} loads hyphenation patterns and exceptions for American English (in files @file{hyphen.us} and @file{hyphenex.us}). A second call to @code{hpf} (for the same language) will replace the hyphenation patterns with the new ones. Invoking @code{hpf} causes an error if there is no current hyphenation language. @endDefreq @Defreq {hcode, c1 code1 c2 code2 @dots{}} @cindex hyphenation code (@code{hcode}) @cindex code, hyphenation (@code{hcode}) Set the hyphenation code of character @var{c1} to @var{code1}, that of @var{c2} to @var{code2}, etc. A hyphenation code must be a single input character (not a special character) other than a digit or a space. Initially each lower-case letter (@samp{a}-@samp{z}) has its hyphenation code set to itself, and each upper-case letter (@samp{A}-@samp{Z}) has a hyphenation code which is the lower-case version of itself. This request is ignored if it has no parameter. @endDefreq @DefreqList {hym, [@Var{length}]} @DefregListEnd {.hym} @cindex hyphenation margin (@code{hym}) @cindex margin for hyphenation (@code{hym}) @cindex @code{ad} request, and hyphenation margin Set the (right) hyphenation margin to @var{length}. If the current adjustment mode is not @samp{b} or @samp{n}, the line is not hyphenated if it is shorter than @var{length}. Without an argument, the hyphenation margin is reset to its default value, which is@tie{}0. The default scaling indicator for this request is @samp{m}. The hyphenation margin is associated with the current environment (@pxref{Environments}). A negative argument resets the hyphenation margin to zero, emitting a warning of type @samp{range}. @cindex hyphenation margin register (@code{.hym}) The current hyphenation margin is available in the @code{.hym} read-only number register. @endDefreq @DefreqList {hys, [@Var{hyphenation_space}]} @DefregListEnd {.hys} @cindex hyphenation space (@code{hys}) @cindex @code{ad} request, and hyphenation space Set the hyphenation space to @var{hyphenation_space}. If the current adjustment mode is @samp{b} or @samp{n}, don't hyphenate the line if it can be justified by adding no more than @var{hyphenation_space} extra space to each word space. Without argument, the hyphenation space is set to its default value, which is@tie{}0. The default scaling indicator for this request is @samp{m}. The hyphenation space is associated with the current environment (@pxref{Environments}). A negative argument resets the hyphenation space to zero, emitting a warning of type @samp{range}. @cindex hyphenation space register (@code{.hys}) The current hyphenation space is available in the @code{.hys} read-only number register. @endDefreq @Defreq {shc, [@Var{glyph}]} @cindex soft hyphen character, setting (@code{shc}) @cindex character, soft hyphen, setting (@code{shc}) @cindex glyph, soft hyphen (@code{hy}) @cindex soft hyphen glyph (@code{hy}) @cindex @code{char} request, and soft hyphen character @cindex @code{tr} request, and soft hyphen character Set the @dfn{soft hyphen character} to @var{glyph}.@footnote{@dfn{Soft hyphen character} is a misnomer since it is an output glyph.} If the argument is omitted, the soft hyphen character is set to the default glyph @code{\(hy} (this is the start-up value of @code{gtroff} also). The soft hyphen character is the glyph that is inserted when a word is hyphenated at a line break. If the soft hyphen character does not exist in the font of the character immediately preceding a potential break point, then the line is not broken at that point. Neither definitions (specified with the @code{char} request) nor translations (specified with the @code{tr} request) are considered when finding the soft hyphen character. @endDefreq @DefreqList {hla, language} @DefregListEnd {.hla} @cindex @code{hpf} request, and hyphenation language @cindex @code{hw} request, and hyphenation language @pindex troffrc @pindex troffrc-end Set the current hyphenation language to the string @var{language}. Hyphenation exceptions specified with the @code{hw} request and hyphenation patterns specified with the @code{hpf} and @code{hpfa} requests are both associated with the current hyphenation language. The @code{hla} request is usually invoked by the @file{troffrc} or the @file{troffrc-end} files; @file{troffrc} sets the default language to @samp{us}. @cindex hyphenation language register (@code{.hla}) The current hyphenation language is available as a string in the read-only number register @samp{.hla}. @Example .ds curr_language \n[.hla] \*[curr_language] @result{} us @endExample @endDefreq @c ===================================================================== @node Manipulating Spacing, Tabs and Fields, Manipulating Hyphenation, gtroff Reference @section Manipulating Spacing @cindex manipulating spacing @cindex spacing, manipulating @Defreq {sp, [@Var{distance}]} Space downwards @var{distance}. With no argument it advances 1@tie{}line. A negative argument causes @code{gtroff} to move up the page the specified distance. If the argument is preceded by a @samp{|} then @code{gtroff} moves that distance from the top of the page. This request causes a line break. The default scaling indicator is @samp{v}. If a vertical trap is sprung during execution of @code{sp}, the amount of vertical space after the trap is discarded. For example, this @Example .de xxx .. . .wh 0 xxx . .pl 5v foo .sp 2 bar .sp 50 baz @endExample @noindent results in @Example foo bar baz @endExample @cindex @code{sp} request, and traps @cindex discarded space in traps @cindex space, discarded, in traps @cindex traps, and discarded space The amount of discarded space is available in the number register @code{.trunc}. To protect @code{sp} against vertical traps, use the @code{vpt} request: @Example .vpt 0 .sp -3 .vpt 1 @endExample @endDefreq @DefreqList {ls, [@Var{nnn}]} @DefregListEnd {.L} @cindex double-spacing (@code{ls}) Output @w{@var{nnn}@minus{}1} blank lines after each line of text. With no argument, @code{gtroff} uses the previous value before the last @code{ls} call. @Example .ls 2 \" This causes double-spaced output .ls 3 \" This causes triple-spaced output .ls \" Again double-spaced @endExample The line spacing is associated with the current environment (@pxref{Environments}). @cindex line spacing register (@code{.L}) The read-only number register @code{.L} contains the current line spacing setting. @endDefreq @xref{Changing Type Sizes}, for the requests @code{vs} and @code{pvs} as alternatives to @code{ls}. @DefescList {\\x, ', spacing, '} @DefregListEnd {.a} Sometimes, extra vertical spacing is only needed occasionally, e.g.@: to allow space for a tall construct (like an equation). The @code{\x} escape does this. The escape is given a numerical argument, usually enclosed in quotes (like @samp{\x'3p'}); the default scaling indicator is @samp{v}. If this number is positive extra vertical space is inserted below the current line. A negative number adds space above. If this escape is used multiple times on the same line, the maximum of the values is used. @xref{Escapes}, for details on parameter delimiting characters. @cindex extra post-vertical line space register (@code{.a}) The @code{.a} read-only number register contains the most recent (nonnegative) extra vertical line space. Using @code{\x} can be necessary in combination with the @code{\b} escape, as the following example shows. @Example This is a test with the \[rs]b escape. .br This is a test with the \[rs]b escape. .br This is a test with \b'xyz'\x'-1m'\x'1m'. .br This is a test with the \[rs]b escape. .br This is a test with the \[rs]b escape. @endExample @noindent produces @Example This is a test with the \b escape. This is a test with the \b escape. x This is a test with y. z This is a test with the \b escape. This is a test with the \b escape. @endExample @endDefesc @DefreqList {ns, } @DefreqItem {rs, } @DefregListEnd {.ns} @cindex @code{sp} request, and no-space mode @cindex no-space mode (@code{ns}) @cindex mode, no-space (@code{ns}) @cindex blank lines, disabling @cindex lines, blank, disabling Enable @dfn{no-space mode}. In this mode, spacing (either via @code{sp} or via blank lines) is disabled. The @code{bp} request to advance to the next page is also disabled, except if it is accompanied by a page number (see @ref{Page Control}, for more information). This mode ends when actual text is output or the @code{rs} request is encountered which ends no-space mode. The read-only number register @code{.ns} is set to@tie{}1 as long as no-space mode is active. This request is useful for macros that conditionally insert vertical space before the text starts (for example, a paragraph macro could insert some space except when it is the first paragraph after a section header). @endDefreq @c ===================================================================== @node Tabs and Fields, Character Translations, Manipulating Spacing, gtroff Reference @section Tabs and Fields @cindex tabs, and fields @cindex fields, and tabs @cindex @acronym{EBCDIC} encoding of a tab A tab character (@acronym{ASCII} char@tie{}9, @acronym{EBCDIC} char@tie{}5) causes a horizontal movement to the next tab stop (much like it did on a typewriter). @Defesc {\\t, , , } @cindex tab character, non-interpreted (@code{\t}) @cindex character, tab, non-interpreted (@code{\t}) This escape is a non-interpreted tab character. In copy mode (@pxref{Copy-in Mode}), @code{\t} is the same as a real tab character. @endDefesc @DefreqList {ta, [@Var{n1} @Var{n2} @dots{} @Var{nn} @t{T} @Var{r1} @Var{r2} @dots{} @Var{rn}]} @DefregListEnd {.tabs} Change tab stop positions. This request takes a series of tab specifiers as arguments (optionally divided into two groups with the letter @samp{T}) which indicate where each tab stop is to be (overriding any previous settings). Tab stops can be specified absolutely, i.e., as the distance from the left margin. For example, the following sets 6@tie{}tab stops every one inch. @Example .ta 1i 2i 3i 4i 5i 6i @endExample Tab stops can also be specified using a leading @samp{+} which means that the specified tab stop is set relative to the previous tab stop. For example, the following is equivalent to the previous example. @Example .ta 1i +1i +1i +1i +1i +1i @endExample @code{gtroff} supports an extended syntax to specify repeat values after the @samp{T} mark (these values are always taken as relative) -- this is the usual way to specify tabs set at equal intervals. The following is, yet again, the same as the previous examples. It does even more since it defines an infinite number of tab stops separated by one inch. @Example .ta T 1i @endExample Now we are ready to interpret the full syntax given at the beginning: Set tabs at positions @var{n1}, @var{n2}, @dots{}, @var{nn} and then set tabs at @var{nn}+@var{r1}, @var{nn}+@var{r2}, @dots{}, @var{nn}+@var{rn} and then at @var{nn}+@var{rn}+@var{r1}, @var{nn}+@var{rn}+@var{r2}, @dots{}, @var{nn}+@var{rn}+@var{rn}, and so on. Example: @samp{4c +6c T 3c 5c 2c} is equivalent to @samp{4c 10c 13c 18c 20c 23c 28c 30c @dots{}}. The material in each tab column (i.e., the column between two tab stops) may be justified to the right or left or centered in the column. This is specified by appending @samp{R}, @samp{L}, or @samp{C} to the tab specifier. The default justification is @samp{L}. Example: @Example .ta 1i 2iC 3iR @endExample Some notes: @itemize @bullet @item The default unit of the @code{ta} request is @samp{m}. @item A tab stop is converted into a non-breakable horizontal movement which can be neither stretched nor squeezed. For example, @Example .ds foo a\tb\tc .ta T 5i \*[foo] @endExample @noindent creates a single line which is a bit longer than 10@tie{}inches (a string is used to show exactly where the tab characters are). Now consider the following: @Example .ds bar a\tb b\tc .ta T 5i \*[bar] @endExample @noindent @code{gtroff} first converts the tab stops of the line into unbreakable horizontal movements, then splits the line after the second @samp{b} (assuming a sufficiently short line length). Usually, this isn't what the user wants. @item Superfluous tabs (i.e., tab characters which do not correspond to a tab stop) are ignored except the first one which delimits the characters belonging to the last tab stop for right-justifying or centering. Consider the following example @Example .ds Z foo\tbar\tfoo .ds ZZ foo\tbar\tfoobar .ds ZZZ foo\tbar\tfoo\tbar .ta 2i 4iR \*[Z] .br \*[ZZ] .br \*[ZZZ] .br @endExample @noindent which produces the following output: @Example foo bar foo foo bar foobar foo bar foobar @endExample @noindent The first line right-justifies the second `foo' relative to the tab stop. The second line right-justifies `foobar'. The third line finally right-justifies only `foo' because of the additional tab character which marks the end of the string belonging to the last defined tab stop. @item Tab stops are associated with the current environment (@pxref{Environments}). @item Calling @code{ta} without an argument removes all tab stops. @item @cindex tab stops, for TTY output devices The start-up value of @code{gtroff} is @w{@samp{T 0.8i}}. @end itemize @cindex tab settings register (@code{.tabs}) The read-only number register @code{.tabs} contains a string representation of the current tab settings suitable for use as an argument to the @code{ta} request. @Example .ds tab-string \n[.tabs] \*[tab-string] @result{} T120u @endExample @cindex @code{.S} register, Plan@tie{}9 alias for @code{.tabs} @cindex @code{.tabs} register, Plan@tie{}9 alias (@code{.S}) The @code{troff} version of the Plan@tie{}9 operating system uses register @code{.S} for the same purpose. @endDefreq @Defreq {tc, [@Var{fill-glyph}]} @cindex tab repetition character (@code{tc}) @cindex character, tab repetition (@code{tc}) @cindex glyph, tab repetition (@code{tc}) Normally @code{gtroff} fills the space to the next tab stop with whitespace. This can be changed with the @code{tc} request. With no argument @code{gtroff} reverts to using whitespace, which is the default. The value of this @dfn{tab repetition character} is associated with the current environment (@pxref{Environments}).@footnote{@dfn{Tab repetition character} is a misnomer since it is an output glyph.} @endDefreq @DefreqList {linetabs, n} @DefregListEnd {.linetabs} @cindex tab, line-tabs mode @cindex line-tabs mode @cindex mode, line-tabs If @var{n} is missing or not zero, enable @dfn{line-tabs} mode, or disable it otherwise (the default). In line-tabs mode, @code{gtroff} computes tab distances relative to the (current) output line instead of the input line. For example, the following code: @Example .ds x a\t\c .ds y b\t\c .ds z c .ta 1i 3i \*x \*y \*z @endExample @noindent in normal mode, results in the output @Example a b c @endExample @noindent in line-tabs mode, the same code outputs @Example a b c @endExample Line-tabs mode is associated with the current environment. The read-only register @code{.linetabs} is set to@tie{}1 if in line-tabs mode, and 0 in normal mode. @endDefreq @menu * Leaders:: * Fields:: @end menu @c --------------------------------------------------------------------- @node Leaders, Fields, Tabs and Fields, Tabs and Fields @subsection Leaders @cindex leaders Sometimes it may may be desirable to use the @code{tc} request to fill a particular tab stop with a given glyph (for example dots in a table of contents), but also normal tab stops on the rest of the line. For this @code{gtroff} provides an alternate tab mechanism, called @dfn{leaders} which does just that. @cindex leader character A leader character (character code@tie{}1) behaves similarly to a tab character: It moves to the next tab stop. The only difference is that for this movement, the fill glyph defaults to a period character and not to space. @Defesc {\\a, , , } @cindex leader character, non-interpreted (@code{\a}) @cindex character, leader, non-interpreted (@code{\a}) This escape is a non-interpreted leader character. In copy mode (@pxref{Copy-in Mode}), @code{\a} is the same as a real leader character. @endDefesc @Defreq {lc, [@Var{fill-glyph}]} @cindex leader repetition character (@code{lc}) @cindex character, leader repetition (@code{lc}) @cindex glyph, leader repetition (@code{lc}) Declare the @dfn{leader repetition character}.@footnote{@dfn{Leader repetition character} is a misnomer since it is an output glyph.} Without an argument, leaders act the same as tabs (i.e., using whitespace for filling). @code{gtroff}'s start-up value is a dot (@samp{.}). The value of the leader repetition character is associated with the current environment (@pxref{Environments}). @endDefreq @cindex table of contents @cindex contents, table of For a table of contents, to name an example, tab stops may be defined so that the section number is one tab stop, the title is the second with the remaining space being filled with a line of dots, and then the page number slightly separated from the dots. @Example .ds entry 1.1\tFoo\a\t12 .lc . .ta 1i 5i +.25i \*[entry] @endExample @noindent This produces @Example 1.1 Foo.......................................... 12 @endExample @c --------------------------------------------------------------------- @node Fields, , Leaders, Tabs and Fields @subsection Fields @cindex fields @cindex field delimiting character (@code{fc}) @cindex delimiting character, for fields (@code{fc}) @cindex character, field delimiting (@code{fc}) @cindex field padding character (@code{fc}) @cindex padding character, for fields (@code{fc}) @cindex character, field padding (@code{fc}) @dfn{Fields} are a more general way of laying out tabular data. A field is defined as the data between a pair of @dfn{delimiting characters}. It contains substrings which are separated by @dfn{padding characters}. The width of a field is the distance on the @emph{input} line from the position where the field starts to the next tab stop. A padding character inserts stretchable space similar to @TeX{}'s @code{\hss} command (thus it can even be negative) to make the sum of all substring lengths plus the stretchable space equal to the field width. If more than one padding character is inserted, the available space is evenly distributed among them. @Defreq {fc, [@Var{delim-char} [@Var{padding-char}]]} Define a delimiting and a padding character for fields. If the latter is missing, the padding character defaults to a space character. If there is no argument at all, the field mechanism is disabled (which is the default). Note that contrary to e.g.@: the tab repetition character, delimiting and padding characters are @emph{not} associated to the current environment (@pxref{Environments}). Example: @Example .fc # ^ .ta T 3i #foo^bar^smurf# .br #foo^^bar^smurf# @endExample @noindent and here the result: @Example foo bar smurf foo bar smurf @endExample @endDefreq @c ===================================================================== @node Character Translations, Troff and Nroff Mode, Tabs and Fields, gtroff Reference @section Character Translations @cindex character translations @cindex translations of characters @cindex control character, changing (@code{cc}) @cindex character, control, changing (@code{cc}) @cindex no-break control character, changing (@code{c2}) @cindex character, no-break control, changing (@code{c2}) @cindex control character, no-break, changing (@code{c2}) The control character (@samp{.}) and the no-break control character (@samp{'}) can be changed with the @code{cc} and @code{c2} requests, respectively. @Defreq {cc, [@Var{c}]} Set the control character to@tie{}@var{c}. With no argument the default control character @samp{.} is restored. The value of the control character is associated with the current environment (@pxref{Environments}). @endDefreq @Defreq {c2, [@Var{c}]} Set the no-break control character to@tie{}@var{c}. With no argument the default control character @samp{'} is restored. The value of the no-break control character is associated with the current environment (@pxref{Environments}). @endDefreq @Defreq {eo, } @cindex disabling @code{\} (@code{eo}) @cindex @code{\}, disabling (@code{eo}) Disable the escape mechanism completely. After executing this request, the backslash character @samp{\} no longer starts an escape sequence. This request can be very helpful in writing macros since it is not necessary then to double the escape character. Here an example: @Example .\" This is a simplified version of the .\" .BR request from the man macro package .eo .de BR . ds result \& . while (\n[.$] >= 2) \@{\ . as result \fB\$1\fR\$2 . shift 2 . \@} . if \n[.$] .as result \fB\$1 \*[result] . ft R .. .ec @endExample @endDefreq @Defreq {ec, [@Var{c}]} @cindex escape character, changing (@code{ec}) @cindex character, escape, changing (@code{ec}) Set the escape character to@tie{}@var{c}. With no argument the default escape character @samp{\} is restored. It can be also used to re-enable the escape mechanism after an @code{eo} request. Note that changing the escape character globally will likely break macro packages since @code{gtroff} has no mechanism to `intern' macros, i.e., to convert a macro definition into an internal form which is independent of its representation (@TeX{} has this mechanism). If a macro is called, it is executed literally. @endDefreq @DefreqList {ecs, } @DefreqListEnd {ecr, } The @code{ecs} request saves the current escape character in an internal register. Use this request in combination with the @code{ec} request to temporarily change the escape character. The @code{ecr} request restores the escape character saved with @code{ecs}. Without a previous call to @code{ecs}, this request sets the escape character to @code{\}. @endDefreq @DefescList {\\\\, , , } @DefescItem {\\e, , , } @DefescListEnd {\\E, , , } Print the current escape character (which is the backslash character @samp{\} by default). @code{\\} is a `delayed' backslash; more precisely, it is the default escape character followed by a backslash, which no longer has special meaning due to the leading escape character. It is @emph{not} an escape sequence in the usual sense! In any unknown escape sequence @code{\@var{X}} the escape character is ignored and @var{X} is printed. But if @var{X} is equal to the current escape character, no warning is emitted. As a consequence, only at top-level or in a diversion a backslash glyph is printed; in copy-in mode, it expands to a single backslash which then combines with the following character to an escape sequence. The @code{\E} escape differs from @code{\e} by printing an escape character that is not interpreted in copy mode. Use this to define strings with escapes that work when used in copy mode (for example, as a macro argument). The following example defines strings to begin and end a superscript: @Example .ds @{ \v'-.3m'\s'\En[.s]*60/100' .ds @} \s0\v'.3m' @endExample Another example to demonstrate the differences between the various escape sequences, using a strange escape character, @samp{-}. @Example .ec - .de xxx --A'123' .. .xxx @result{} -A'foo' @endExample @noindent The result is surprising for most users, expecting @samp{1} since @samp{foo} is a valid identifier. What has happened? As mentioned above, the leading escape character makes the following character ordinary. Written with the default escape character the sequence @samp{--} becomes @samp{\-} -- this is the minus sign. If the escape character followed by itself is a valid escape sequence, only @code{\E} yields the expected result: @Example .ec - .de xxx -EA'123' .. .xxx @result{} 1 @endExample @endDefesc @Defesc {\\., , , } Similar to @code{\\}, the sequence @code{\.} isn't a real escape sequence. As before, a warning message is suppressed if the escape character is followed by a dot, and the dot itself is printed. @Example .de foo . nop foo . . de bar . nop bar \\.. . .. .foo .bar @result{} foo bar @endExample @noindent The first backslash is consumed while the macro is read, and the second is swallowed while exexuting macro @code{foo}. @endDefesc A @dfn{translation} is a mapping of an input character to an output glyph. The mapping occurs at output time, i.e., the input character gets assigned the metric information of the mapped output character right before input tokens are converted to nodes (@pxref{Gtroff Internals}, for more on this process). @DefreqList {tr, @Var{a}@Var{b}@Var{c}@Var{d}@dots{}} @DefreqListEnd {trin, @Var{a}@Var{b}@Var{c}@Var{d}@dots{}} Translate character @var{a} to glyph@tie{}@var{b}, character @var{c} to glyph@tie{}@var{d}, etc. If there is an odd number of arguments, the last one is translated to an unstretchable space (@w{@samp{\ }}). The @code{trin} request is identical to @code{tr}, but when you unformat a diversion with @code{asciify} it ignores the translation. @xref{Diversions}, for details about the @code{asciify} request. Some notes: @itemize @bullet @item @cindex @code{\(}, and translations @cindex @code{\[}, and translations @cindex @code{\'}, and translations @cindex @code{\`}, and translations @cindex @code{\-}, and translations @cindex @code{\_}, and translations @cindex @code{\C}, and translations @cindex @code{\N}, and translations @cindex @code{char} request, and translations @cindex special characters @cindex character, special @cindex numbered glyph (@code{\N}) @cindex glyph, numbered (@code{\N}) Special characters (@code{\(@var{xx}}, @code{\[@var{xxx}]}, @code{\C'@var{xxx}'}, @code{\'}, @code{\`}, @code{\-}, @code{\_}), glyphs defined with the @code{char} request, and numbered glyphs (@code{\N'@var{xxx}'}) can be translated also. @item @cindex @code{\e}, and translations The @code{\e} escape can be translated also. @item @cindex @code{\%}, and translations @cindex @code{\~}, and translations Characters can be mapped onto the @code{\%} and @code{\~} escapes (but @code{\%} and @code{\~} can't be mapped onto another glyph). @item @cindex backspace character, and translations @cindex character, backspace, and translations @cindex leader character, and translations @cindex character, leader, and translations @cindex newline character, and translations @cindex character, newline, and translations @cindex tab character, and translations @cindex character, tab, and translations @cindex @code{\a}, and translations @cindex @code{\t}, and translations The following characters can't be translated: space (with one exception, see below), backspace, newline, leader (and @code{\a}), tab (and @code{\t}). @item @cindex @code{shc} request, and translations Translations are not considered for finding the soft hyphen character set with the @code{shc} request. @item @cindex @code{\&}, and translations The pair @samp{@var{c}\&} (this is an arbitrary character@tie{}@var{c} followed by the zero width space character) maps this character to nothing. @Example .tr a\& foo bar @result{} foo br @endExample @noindent It is even possible to map the space character to nothing: @Example .tr aa \& foo bar @result{} foobar @endExample @noindent As shown in the example, the space character can't be the first character/glyph pair as an argument of @code{tr}. Additionally, it is not possible to map the space character to any other glyph; requests like @w{@samp{.tr aa x}} undo @w{@samp{.tr aa \&}} instead. If justification is active, lines are justified in spite of the `empty' space character (but there is no minimal distance, i.e.@: the space character, between words). @item After an output glyph has been constructed (this happens at the moment immediately before the glyph is appended to an output glyph list, either by direct output, in a macro, diversion, or string), it is no longer affected by @code{tr}. @item Translating character to glyphs where one of them or both are undefined is possible also; @code{tr} does not check whether the entities in its argument do exist. @xref{Gtroff Internals}. @item @code{troff} no longer has a hard-coded dependency on @w{Latin-1}; all @code{char@var{XXX}} entities have been removed from the font description files. This has a notable consequence which shows up in warnings like @code{can't find character with input code @var{XXX}} if the @code{tr} request isn't handled properly. Consider the following translation: @Example .tr @'e@'E @endExample @noindent This maps input character @code{@'e} onto glyph @code{@'E}, which is identical to glyph @code{char201}. But this glyph intentionally doesn't exist! Instead, @code{\[char201]} is treated as an input character entity and is by default mapped onto @code{\['E]}, and @code{gtroff} doesn't handle translations of translations. The right way to write the above translation is @Example .tr @'e\['E] @endExample @noindent With other words, the first argument of @code{tr} should be an input character or entity, and the second one a glyph entity. @item Without an argument, the @code{tr} request is ignored. @end itemize @endDefreq @Defreq {trnt, @Var{a}@Var{b}@Var{c}@Var{d}@dots{}} @cindex @code{\!}, and @code{trnt} @code{trnt} is the same as the @code{tr} request except that the translations do not apply to text that is transparently throughput into a diversion with @code{\!}. @xref{Diversions}, for more information. For example, @Example .tr ab .di x \!.tm a .di .x @endExample @noindent prints @samp{b} to the standard error stream; if @code{trnt} is used instead of @code{tr} it prints @samp{a}. @endDefreq @c ===================================================================== @node Troff and Nroff Mode, Line Layout, Character Translations, gtroff Reference @section Troff and Nroff Mode @cindex troff mode @cindex mode, troff @cindex nroff mode @cindex mode, nroff Originally, @code{nroff} and @code{troff} were two separate programs, the former for TTY output, the latter for everything else. With GNU @code{troff}, both programs are merged into one executable, sending its output to a device driver (@code{grotty} for TTY devices, @code{grops} for @sc{PostScript}, etc.) which interprets the intermediate output of @code{gtroff}. For @acronym{UNIX} @code{troff} it makes sense to talk about @dfn{Nroff mode} and @dfn{Troff mode} since the differences are hardcoded. For GNU @code{troff}, this distinction is not appropriate because @code{gtroff} simply takes the information given in the font files for a particular device without handling requests specially if a TTY output device is used. Usually, a macro package can be used with all output devices. Nevertheless, it is sometimes necessary to make a distinction between TTY and non-TTY devices: @code{gtroff} provides two built-in conditions @samp{n} and @samp{t} for the @code{if}, @code{ie}, and @code{while} requests to decide whether @code{gtroff} shall behave like @code{nroff} or like @code{troff}. @Defreq {troff, } @pindex troffrc @pindex troffrc-end Make the @samp{t} built-in condition true (and the @samp{n} built-in condition false) for @code{if}, @code{ie}, and @code{while} conditional requests. This is the default if @code{gtroff} (@emph{not} @code{groff}) is started with the @option{-R} switch to avoid loading of the start-up files @file{troffrc} and @file{troffrc-end}. Without @option{-R}, @code{gtroff} stays in troff mode if the output device is not a TTY (e.g.@: `ps'). @endDefreq @Defreq {nroff, } @pindex tty.tmac Make the @samp{n} built-in condition true (and the @samp{t} built-in condition false) for @code{if}, @code{ie}, and @code{while} conditional requests. This is the default if @code{gtroff} uses a TTY output device; the code for switching to nroff mode is in the file @file{tty.tmac} which is loaded by the start-up file @code{troffrc}. @endDefreq @xref{Conditionals and Loops}, for more details on built-in conditions. @c ===================================================================== @node Line Layout, Line Control, Troff and Nroff Mode, gtroff Reference @section Line Layout @cindex line layout @cindex layout, line @cindex dimensions, line @cindex line dimensions The following drawing shows the dimensions which @code{gtroff} uses for placing a line of output onto the page. They are labeled with the request which manipulates each dimension. @Example -->| in |<-- |<-----------ll------------>| +----+----+----------------------+----+ | : : : | +----+----+----------------------+----+ -->| po |<-- |<--------paper width---------------->| @endExample @noindent These dimensions are: @ftable @code @item po @cindex left margin (@code{po}) @cindex margin, left (@code{po}) @cindex page offset (@code{po}) @cindex offset, page (@code{po}) @dfn{Page offset} -- this is the leftmost position of text on the final output, defining the @dfn{left margin}. @item in @cindex indentation (@code{in}) @cindex line indentation (@code{in}) @dfn{Indentation} -- this is the distance from the left margin where text is printed. @item ll @cindex line length (@code{ll}) @cindex length of line (@code{ll}) @dfn{Line length} -- this is the distance from the left margin to right margin. @end ftable A simple demonstration: @Example .ll 3i This is text without indentation. The line length has been set to 3\~inch. .in +.5i .ll -.5i Now the left and right margins are both increased. .in .ll Calling .in and .ll without parameters restore the previous values. @endExample Result: @Example This is text without indenta- tion. The line length has been set to 3 inch. Now the left and right margins are both increased. Calling .in and .ll without parameters restore the previ- ous values. @endExample @DefreqList {po, [@Var{offset}]} @DefreqItem {po, @t{+}@Var{offset}} @DefreqItem {po, @t{-}@Var{offset}} @DefregListEnd {.o} @pindex troffrc Set horizontal page offset to @var{offset} (or increment or decrement the current value by @var{offset}). Note that this request does not cause a break, so changing the page offset in the middle of text being filled may not yield the expected result. The initial value is 1@dmn{i}. For TTY output devices, it is set to 0 in the startup file @file{troffrc}; the default scaling indicator is @samp{m} (and not @samp{v} as incorrectly documented in the original @acronym{UNIX} troff manual). The current page offset can be found in the read-only number register @samp{.o}. If @code{po} is called without an argument, the page offset is reset to the previous value before the last call to @code{po}. @Example .po 3i \n[.o] @result{} 720 .po -1i \n[.o] @result{} 480 .po \n[.o] @result{} 720 @endExample @endDefreq @DefreqList {in, [@Var{indent}]} @DefreqItem {in, @t{+}@Var{indent}} @DefreqItem {in, @t{-}@Var{indent}} @DefregListEnd {.i} Set indentation to @var{indent} (or increment or decrement the current value by @var{indent}). This request causes a break. Initially, there is no indentation. If @code{in} is called without an argument, the indentation is reset to the previous value before the last call to @code{in}. The default scaling indicator is @samp{m}. The indentation is associated with the current environment (@pxref{Environments}). If a negative indentation value is specified (which is not allowed), @code{gtroff} emits a warning of type @samp{range} and sets the indentation to zero. The effect of @code{in} is delayed until a partially collected line (if it exists) is output. A temporary indent value is reset to zero also. The current indentation (as set by @code{in}) can be found in the read-only number register @samp{.i}. @endDefreq @DefreqList {ti, offset} @DefreqItem {ti, @t{+}@Var{offset}} @DefreqItem {ti, @t{-}@Var{offset}} @DefregListEnd {.in} Temporarily indent the next output line by @var{offset}. If an increment or decrement value is specified, adjust the temporary indentation relative to the value set by the @code{in} request. This request causes a break; its value is associated with the current environment (@pxref{Environments}). The default scaling indicator is @samp{m}. A call of @code{ti} without an argument is ignored. If the total indentation value is negative (which is not allowed), @code{gtroff} emits a warning of type @samp{range} and sets the temporary indentation to zero. `Total indentation' is either @var{offset} if specified as an absolute value, or the temporary plus normal indentation, if @var{offset} is given as a relative value. The effect of @code{ti} is delayed until a partially collected line (if it exists) is output. The read-only number register @code{.in} is the indentation that applies to the current output line. The difference between @code{.i} and @code{.in} is that the latter takes into account whether a partially collected line still uses the old indentation value or a temporary indentation value is active. @endDefreq @DefreqList {ll, [@Var{length}]} @DefreqItem {ll, @t{+}@Var{length}} @DefreqItem {ll, @t{-}@Var{length}} @DefregItem {.l} @DefregListEnd {.ll} Set the line length to @var{length} (or increment or decrement the current value by @var{length}). Initially, the line length is set to 6.5@dmn{i}. The effect of @code{ll} is delayed until a partially collected line (if it exists) is output. The default scaling indicator is @samp{m}. If @code{ll} is called without an argument, the line length is reset to the previous value before the last call to @code{ll}. If a negative line length is specified (which is not allowed), @code{gtroff} emits a warning of type @samp{range} and sets the line length to zero. The line length is associated with the current environment (@pxref{Environments}). @cindex line length register (@code{.l}) The current line length (as set by @code{ll}) can be found in the read-only number register @samp{.l}. The read-only number register @code{.ll} is the line length that applies to the current output line. Similar to @code{.i} and @code{.in}, the difference between @code{.l} and @code{.ll} is that the latter takes into account whether a partially collected line still uses the old line length value. @endDefreq @c ===================================================================== @node Line Control, Page Layout, Line Layout, gtroff Reference @section Line Control @cindex line control @cindex control, line It is important to understand how @code{gtroff} handles input and output lines. Many escapes use positioning relative to the input line. For example, this @Example This is a \h'|1.2i'test. This is a \h'|1.2i'test. @endExample @noindent produces @Example This is a test. This is a test. @endExample The main usage of this feature is to define macros which act exactly at the place where called. @Example .\" A simple macro to underline a word .de underline . nop \\$1\l'|0\[ul]' .. @endExample @noindent In the above example, @samp{|0} specifies a negative distance from the current position (at the end of the just emitted argument @code{\$1}) back to the beginning of the input line. Thus, the @samp{\l} escape draws a line from right to left. @cindex input line continuation (@code{\}) @cindex line, input, continuation (@code{\}) @cindex continuation, input line (@code{\}) @cindex output line, continuation (@code{\c}) @cindex line, output, continuation (@code{\c}) @cindex continuation, output line (@code{\c}) @cindex interrupted line @cindex line, interrupted @code{gtroff} makes a difference between input and output line continuation; the latter is also called @dfn{interrupting} a line. @DefescList {\\@key{RET}, , ,} @DefescItem {\\c, , ,} @DefregListEnd{.int} Continue a line. @code{\@key{RET}} (this is a backslash at the end of a line immediately followed by a newline) works on the input level, suppressing the effects of the following newline in the input. @Example This is a \ .test @result{} This is a .test @endExample The @samp{|} operator is also affected. @cindex @code{\R}, after @code{\c} @code{\c} works on the output level. Anything after this escape on the same line is ignored, except @code{\R} which works as usual. Anything before @code{\c} on the same line will be appended to the current partial output line. The next non-command line after an interrupted line counts as a new input line. The visual results depend on whether no-fill mode is active. @itemize @bullet @item @cindex @code{\c}, and no-fill mode @cindex no-fill mode, and @code{\c} @cindex mode, no-fill, and @code{\c} If no-fill mode is active (using the @code{nf} request), the next input text line after @code{\c} will be handled as a continuation of the same input text line. @Example .nf This is a \c test. @result{} This is a test. @endExample @item @cindex @code{\c}, and fill mode @cindex fill mode, and @code{\c} @cindex mode, fill, and @code{\c} If fill mode is active (using the @code{fi} request), a word interrupted with @code{\c} will be continued with the text on the next input text line, without an intervening space. @Example This is a te\c st. @result{} This is a test. @endExample @end itemize Note that an intervening control line which causes a break is stronger than @code{\c}, flushing out the current partial line in the usual way. @cindex interrupted line register (@code{.int}) The @code{.int} register contains a positive value if the last output line was interrupted with @code{\c}; this is associated with the current environment (@pxref{Environments}). @endDefesc @c ===================================================================== @node Page Layout, Page Control, Line Control, gtroff Reference @section Page Layout @cindex page layout @cindex layout, page @code{gtroff} provides some very primitive operations for controlling page layout. @DefreqList {pl, [@Var{length}]} @DefreqItem {pl, @t{+}@Var{length}} @DefreqItem {pl, @t{-}@Var{length}} @DefregListEnd {.p} @cindex page length (@code{pl}) @cindex length of page (@code{pl}) Set the @dfn{page length} to @var{length} (or increment or decrement the current value by @var{length}). This is the length of the physical output page. The default scaling indicator is @samp{v}. @cindex page length register (@code{.p}) The current setting can be found in the read-only number register @samp{.p}. @cindex top margin @cindex margin, top @cindex bottom margin @cindex margin, bottom Note that this only specifies the size of the page, not the top and bottom margins. Those are not set by @code{gtroff} directly. @xref{Traps}, for further information on how to do this. Negative @code{pl} values are possible also, but not very useful: No trap is sprung, and each line is output on a single page (thus suppressing all vertical spacing). If no argument or an invalid argument is given, @code{pl} sets the page length to 11@dmn{i}. @endDefreq @cindex headers @cindex footers @cindex titles @code{gtroff} provides several operations which help in setting up top and bottom titles (or headers and footers). @Defreq {tl, @t{'}@Var{left}@t{'}@Var{center}@t{'}@Var{right}@t{'}} @cindex title line (@code{tl}) @cindex three-part title (@code{tl}) @cindex page number character (@code{%}) Print a @dfn{title line}. It consists of three parts: a left justified portion, a centered portion, and a right justified portion. The argument separator @samp{'} can be replaced with any character not occurring in the title line. The @samp{%} character is replaced with the current page number. This character can be changed with the @code{pc} request (see below). Without argument, @code{tl} is ignored. Some notes: @itemize @bullet @item A title line is not restricted to the top or bottom of a page. @item @code{tl} prints the title line immediately, ignoring a partially filled line (which stays untouched). @item It is not an error to omit closing delimiters. For example, @w{@samp{.tl /foo}} is equivalent to @w{@samp{.tl /foo///}}: It prints a title line with the left justified word @samp{foo}; the centered and right justfied parts are empty. @item @code{tl} accepts the same parameter delimiting characters as the @code{\A} escape; see @ref{Escapes}. @end itemize @endDefreq @DefreqList {lt, [@Var{length}]} @DefreqItem {lt, @t{+}@Var{length}} @DefreqItem {lt, @t{-}@Var{length}} @DefregListEnd {.lt} @cindex length of title line (@code{lt}) @cindex title line, length (@code{lt}) @cindex title line length register (@code{.lt}) The title line is printed using its own line length, which is specified (or incremented or decremented) with the @code{lt} request. Initially, the title line length is set to 6.5@dmn{i}. If a negative line length is specified (which is not allowed), @code{gtroff} emits a warning of type @samp{range} and sets the title line length to zero. The default scaling indicator is @samp{m}. If @code{lt} is called without an argument, the title length is reset to the previous value before the last call to @code{lt}. The current setting of this is available in the @code{.lt} read-only number register; it is associated with the current environment (@pxref{Environments}). @endDefreq @DefreqList {pn, page} @DefreqItem {pn, @t{+}@Var{page}} @DefreqItem {pn, @t{-}@Var{page}} @DefregListEnd {.pn} @cindex page number (@code{pn}) @cindex number, page (@code{pn}) Change (increase or decrease) the page number of the @emph{next} page. The only argument is the page number; the request is ignored without a parameter. The read-only number register @code{.pn} contains the number of the next page: either the value set by a @code{pn} request, or the number of the current page plus@tie{}1. @endDefreq @Defreq {pc, [@Var{char}]} @cindex changing the page number character (@code{pc}) @cindex page number character, changing (@code{pc}) @vindex % Change the page number character (used by the @code{tl} request) to a different character. With no argument, this mechanism is disabled. Note that this doesn't affect the number register@tie{}@code{%}. @endDefreq @xref{Traps}. @c ===================================================================== @node Page Control, Fonts and Symbols, Page Layout, gtroff Reference @section Page Control @cindex page control @cindex control, page @DefreqList {bp, [@Var{page}]} @DefreqItem {bp, @t{+}@Var{page}} @DefreqItem {bp, @t{-}@Var{page}} @DefregListEnd {%} @cindex new page (@code{bp}) @cindex page, new (@code{bp}) Stop processing the current page and move to the next page. This request causes a break. It can also take an argument to set (increase, decrease) the page number of the next page (which actually becomes the current page after @code{bp} has finished). The difference between @code{bp} and @code{pn} is that @code{pn} does not cause a break or actually eject a page. @xref{Page Layout}. @Example .de newpage \" define macro 'bp \" begin page 'sp .5i \" vertical space .tl 'left top'center top'right top' \" title 'sp .3i \" vertical space .. \" end macro @endExample @cindex @code{bp} request, and top-level diversion @cindex top-level diversion, and @code{bp} @cindex diversion, top-level, and @code{bp} @code{bp} has no effect if not called within the top-level diversion (@pxref{Diversions}). @cindex page number register (@code{%}) @cindex current page number (@code{%}) The read-write register@tie{}@code{%} holds the current page number. The number register @code{.pe} is set to@tie{}1 while @code{bp} is active. @xref{Page Location Traps}. @endDefreq @Defreq {ne, [@Var{space}]} @cindex orphan lines, preventing with @code{ne} @cindex conditional page break (@code{ne}) @cindex page break, conditional (@code{ne}) It is often necessary to force a certain amount of space before a new page occurs. This is most useful to make sure that there is not a single @dfn{orphan} line left at the bottom of a page. The @code{ne} request ensures that there is a certain distance, specified by the first argument, before the next page is triggered (see @ref{Traps}, for further information). The default scaling indicator for @code{ne} is @samp{v}; the default value of @var{space} is@tie{}1@dmn{v} if no argument is given. For example, to make sure that no fewer than 2@tie{}lines get orphaned, do the following before each paragraph: @Example .ne 2 text text text @endExample @code{ne} will then automatically cause a page break if there is space for one line only. @endDefreq @DefreqList {sv, [@Var{space}]} @DefreqListEnd {os, } @cindex @code{ne} request, comparison with @code{sv} @code{sv} is similar to the @code{ne} request; it reserves the specified amount of vertical space. If the desired amount of space exists before the next trap (or the bottom page boundary if no trap is set), the space is output immediately (ignoring a partially filled line which stays untouched). If there is not enough space, it is stored for later output via the @code{os} request. The default value is@tie{}1@dmn{v} if no argument is given; the default scaling indicator is @samp{v}. @cindex @code{sv} request, and no-space mode @cindex @code{os} request, and no-space mode Both @code{sv} and @code{os} ignore no-space mode. While the @code{sv} request allows negative values for @var{space}, @code{os} will ignore them. @endDefreq @Defreg {nl} @cindex current vertical position (@code{nl}) @cindex vertical position, current (@code{nl}) @cindex position, vertical, current (@code{nl}) This register contains the current vertical position. If the vertical position is zero and the top of page transition hasn't happened yet, @code{nl} is set to negative value. @code{gtroff} itself does this at the very beginning of a document before anything has been printed, but the main usage is to plant a header trap on a page if this page has already started. Consider the following: @Example .de xxx . sp . tl ''Header'' . sp .. . First page. .bp .wh 0 xxx .nr nl (-1) Second page. @endExample @noindent Result: @Example First page. ... Header Second page. ... @endExample @noindent Without resetting @code{nl} to a negative value, the just planted trap would be active beginning with the @emph{next} page, not the current one. @xref{Diversions}, for a comparison with the @code{.h} and @code{.d} registers. @endDefreg @c ===================================================================== @node Fonts and Symbols, Sizes, Page Control, gtroff Reference @section Fonts and Symbols @cindex fonts @code{gtroff} can switch fonts at any point in the text. The basic set of fonts is @samp{R}, @samp{I}, @samp{B}, and @samp{BI}. These are Times Roman, Italic, Bold, and Bold Italic. For non-TTY devices, there is also at least one symbol font which contains various special symbols (Greek, mathematics). @menu * Changing Fonts:: * Font Families:: * Font Positions:: * Using Symbols:: * Special Fonts:: * Artificial Fonts:: * Ligatures and Kerning:: @end menu @c --------------------------------------------------------------------- @node Changing Fonts, Font Families, Fonts and Symbols, Fonts and Symbols @subsection Changing Fonts @cindex fonts @DefreqList {ft, [@Var{font}]} @DefescItem {\\f, , f, } @DefescItem {\\f, @lparen{}, fn, } @DefescListEnd {\\f, @lbrack{}, font, @rbrack} @cindex changing fonts (@code{ft}, @code{\f}) @cindex fonts, changing (@code{ft}, @code{\f}) @cindex @code{sty} request, and changing fonts @cindex @code{fam} request, and changing fonts @cindex @code{\F}, and changing fonts @kindex styles @kindex family @pindex DESC The @code{ft} request and the @code{\f} escape change the current font to @var{font} (one-character name@tie{}@var{f}, two-character name @var{fn}). If @var{font} is a style name (as set with the @code{sty} request or with the @code{styles} command in the @file{DESC} file), use it within the current font family (as set with the @code{fam} request, @code{\F} escape, or with the @code{family} command in the @file{DESC} file). @cindex previous font (@code{ft}, @code{\f[]}, @code{\fP}) @cindex font, previous (@code{ft}, @code{\f[]}, @code{\fP}) With no argument or using @samp{P} as an argument, @code{.ft} switches to the previous font. Use @code{\f[]} to do this with the escape. The old syntax forms @code{\fP} or @code{\f[P]} are also supported. Fonts are generally specified as upper-case strings, which are usually 1@tie{}to 4 characters representing an abbreviation or acronym of the font name. This is no limitation, just a convention. The example below produces two identical lines. @Example eggs, bacon, .ft B spam .ft and sausage. eggs, bacon, \fBspam\fP and sausage. @endExample Note that @code{\f} doesn't produce an input token in @code{gtroff}. As a consequence, it can be used in requests like @code{mc} (which expects a single character as an argument) to change the font on the fly: @Example .mc \f[I]x\f[] @endExample @xref{Font Positions}, for an alternative syntax. @endDefreq @Defreq {ftr, f [@Var{g}]} @cindex @code{ft} request, and font translations @cindex @code{ul} request, and font translations @cindex @code{bd} request, and font translations @cindex @code{\f}, and font translations @cindex @code{cs} request, and font translations @cindex @code{tkf} request, and font translations @cindex @code{special} request, and font translations @cindex @code{fspecial} request, and font translations @cindex @code{fp} request, and font translations @cindex @code{sty} request, and font translations Translate font@tie{}@var{f} to font@tie{}@var{g}. Whenever a font named@tie{}@var{f} is referred to in a @code{\f} escape sequence, or in the @code{ft}, @code{ul}, @code{bd}, @code{cs}, @code{tkf}, @code{special}, @code{fspecial}, @code{fp}, or @code{sty} requests, font@tie{}@var{g} is used. If @var{g} is missing or equal to@tie{}@var{f} the translation is undone. @endDefreq @c --------------------------------------------------------------------- @node Font Families, Font Positions, Changing Fonts, Fonts and Symbols @subsection Font Families @cindex font families @cindex families, font @cindex font styles @cindex styles, font Due to the variety of fonts available, @code{gtroff} has added the concept of @dfn{font families} and @dfn{font styles}. The fonts are specified as the concatenation of the font family and style. Specifying a font without the family part causes @code{gtroff} to use that style of the current family. @cindex PostScript fonts @cindex fonts, PostScript Currently, fonts for the devices @option{-Tps}, @option{-Tdvi}, and @option{-Tlbp} are set up to this mechanism. By default, @code{gtroff} uses the Times family with the four styles @samp{R}, @samp{I}, @samp{B}, and @samp{BI}. This way, it is possible to use the basic four fonts and to select a different font family on the command line (@pxref{Groff Options}). @DefreqList {fam, [@Var{family}]} @DefregItem {.fam} @DefescItem {\\F, , f, } @DefescItem {\\F, @lparen{}, fm, } @DefescItem {\\F, @lbrack{}, family, @rbrack} @DefregListEnd {.fn} @cindex changing font family (@code{fam}, @code{\F}) @cindex font family, changing (@code{fam}, @code{\F}) Switch font family to @var{family} (one-character name@tie{}@var{f}, two-character name @var{fm}). If no argument is given, switch back to the previous font family. Use @code{\F[]} to do this with the escape. Note that @code{\FP} doesn't work; it selects font family @samp{P} instead. The value at start-up is @samp{T}. The current font family is available in the read-only number register @samp{.fam} (this is a string-valued register); it is associated with the current environment. @Example spam, .fam H \" helvetica family spam, \" used font is family H + style R = HR .ft B \" family H + style B = font HB spam, .fam T \" times family spam, \" used font is family T + style B = TB .ft AR \" font AR (not a style) baked beans, .ft R \" family T + style R = font TR and spam. @endExample Note that @code{\F} doesn't produce an input token in @code{gtroff}. As a consequence, it can be used in requests like @code{mc} (which expects a single character as an argument) to change the font family on the fly: @Example .mc \F[P]x\F[] @endExample The @samp{.fn} register contains the current @dfn{real font name} of the current font. This is a string-valued register. If the current font is a style, the value of @code{\n[.fn]} is the proper concatenation of family and style name. @endDefreq @Defreq {sty, n style} @cindex changing font style (@code{sty}) @cindex font style, changing (@code{sty}) @cindex @code{cs} request, and font styles @cindex @code{bd} request, and font styles @cindex @code{tkf} request, and font styles @cindex @code{uf} request, and font styles @cindex @code{fspecial} request, and font styles Associate @var{style} with font position@tie{}@var{n}. A font position can be associated either with a font or with a style. The current font is the index of a font position and so is also either a font or a style. If it is a style, the font that is actually used is the font which name is the concatenation of the name of the current family and the name of the current style. For example, if the current font is@tie{}1 and font position@tie{}1 is associated with style @samp{R} and the current font family is @samp{T}, then font @samp{TR} will be used. If the current font is not a style, then the current family is ignored. If the requests @code{cs}, @code{bd}, @code{tkf}, @code{uf}, or @code{fspecial} are applied to a style, they will instead be applied to the member of the current family corresponding to that style. @var{n}@tie{}must be a non-negative integer value. @pindex DESC @kindex styles The default family can be set with the @option{-f} option (@pxref{Groff Options}). The @code{styles} command in the @file{DESC} file controls which font positions (if any) are initially associated with styles rather than fonts. For example, the default setting for @sc{PostScript} fonts @Example styles R I B BI @endExample @noindent is equivalent to @Example .sty 1 R .sty 2 I .sty 3 B .sty 4 BI @endExample @code{fam} and @code{\F} always check whether the current font position is valid; this can give surprising results if the current font position is associated with a style. In the following example, we want to access the @sc{PostScript} font @code{FooBar} from the font family @code{Foo}: @Example .sty \n[.fp] Bar .fam Foo @result{} warning: can't find font `FooR' @endExample @noindent The default font position at start-up is@tie{}1; for the @sc{PostScript} device, this is associated with style @samp{R}, so @code{gtroff} tries to open @code{FooR}. A solution to this problem is to use a dummy font like the following: @Example .fp 0 dummy TR \" set up dummy font at position 0 .sty \n[.fp] Bar \" register style `Bar' .ft 0 \" switch to font at position 0 .fam Foo \" activate family `Foo' .ft Bar \" switch to font `FooBar' @endExample @xref{Font Positions}. @endDefreq @c --------------------------------------------------------------------- @node Font Positions, Using Symbols, Font Families, Fonts and Symbols @subsection Font Positions @cindex font positions @cindex positions, font For the sake of old phototypesetters and compatibility with old versions of @code{troff}, @code{gtroff} has the concept of font @dfn{positions}, on which various fonts are mounted. @DefreqList {fp, pos font [@Var{external-name}]} @DefregItem {.f} @DefregListEnd {.fp} @cindex mounting font (@code{fp}) @cindex font, mounting (@code{fp}) Mount font @var{font} at position @var{pos} (which must be a non-negative integer). This numeric position can then be referred to with font changing commands. When @code{gtroff} starts it is using font position@tie{}1 (which must exist; position@tie{}0 is unused usually at start-up). @cindex font position register (@code{.f}) The current font in use, as a font position, is available in the read-only number register @samp{.f}. This can be useful to remember the current font for later recall. It is associated with the current environment (@pxref{Environments}). @Example .nr save-font \n[.f] .ft B ... text text text ... .ft \n[save-font] @endExample @cindex next free font position register (@code{.fp}) The number of the next free font position is available in the read-only number register @samp{.fp}. This is useful when mounting a new font, like so: @Example .fp \n[.fp] NEATOFONT @endExample @pindex DESC@r{, and font mounting} Fonts not listed in the @file{DESC} file are automatically mounted on the next available font position when they are referenced. If a font is to be mounted explicitly with the @code{fp} request on an unused font position, it should be mounted on the first unused font position, which can be found in the @code{.fp} register. Although @code{gtroff} does not enforce this strictly, it is not allowed to mount a font at a position whose number is much greater (approx.@: 1000 positions) than that of any currently used position. The @code{fp} request has an optional third argument. This argument gives the external name of the font, which is used for finding the font description file. The second argument gives the internal name of the font which is used to refer to the font in @code{gtroff} after it has been mounted. If there is no third argument then the internal name is used as the external name. This feature makes it possible to use fonts with long names in compatibility mode. @endDefreq Both the @code{ft} request and the @code{\f} escape have alternative syntax forms to access font positions. @DefreqList {ft, nnn} @DefescItem {\\f, , n, } @DefescItem {\\f, @lparen{}, nn, } @DefescListEnd {\\f, @lbrack{}, nnn, @rbrack} @cindex changing font position (@code{\f}) @cindex font position, changing (@code{\f}) @cindex @code{sty} request, and font positions @cindex @code{fam} request, and font positions @cindex @code{\F}, and font positions @kindex styles @kindex family @pindex DESC Change the current font position to @var{nnn} (one-digit position@tie{}@var{n}, two-digit position @var{nn}), which must be a non-negative integer. If @var{nnn} is associated with a style (as set with the @code{sty} request or with the @code{styles} command in the @file{DESC} file), use it within the current font family (as set with the @code{fam} request, the @code{\F} escape, or with the @code{family} command in the @file{DESC} file). @Example this is font 1 .ft 2 this is font 2 .ft \" switch back to font 1 .ft 3 this is font 3 .ft this is font 1 again @endExample @xref{Changing Fonts}, for the standard syntax form. @endDefreq @c --------------------------------------------------------------------- @node Using Symbols, Special Fonts, Font Positions, Fonts and Symbols @subsection Using Symbols @cindex using symbols @cindex symbols, using @cindex glyph @cindex character @cindex ligature A @dfn{glyph} is a graphical representation of a @dfn{character}. While a character is an abstract entity containing semantic information, a glyph is something which can be actually seen on screen or paper. It is possible that a character has multiple glyph representation forms (for example, the character `A' can be either written in a roman or an italic font, yielding two different glyphs); sometimes more than one character maps to a single glyph (this is a @dfn{ligature} -- the most common is `fi'). @cindex symbol @cindex special fonts @kindex fonts @pindex DESC @cindex @code{special} request, and glyph search order @cindex @code{fspecial} request, and glyph search order A @dfn{symbol} is simply a named glyph. Within @code{gtroff}, all glyph names of a particular font are defined in its font file. If the user requests a glyph not available in this font, @code{gtroff} looks up an ordered list of @dfn{special fonts}. By default, the @sc{PostScript} output device supports the two special fonts @samp{SS} (slanted symbols) and @samp{S} (symbols) (the former is looked up before the latter). Other output devices use different names for special fonts. Fonts mounted with the @code{fonts} keyword in the @file{DESC} file are globally available. To install additional special fonts locally (i.e.@: for a particular font), use the @code{fspecial} request. Here the exact rules how @code{gtroff} searches a given symbol: @itemize @bullet @item If the symbol has been defined with the @code{char} request, use it. This hides a symbol with the same name in the current font. @item Check the current font. @item If the symbol has been defined with the @code{fchar} request, use it. @item Check whether the current font has a font-specific list of special fonts; test all fonts in the order of appearance in the last @code{fspecial} call if appropriate. @item If the symbol has been defined with the @code{fschar} request for the current font, use it. @item Check all fonts in the order of appearance in the last @code{special} call. @item If the symbol has been defined with the @code{schar} request, use it. @item As a last resort, consult all fonts loaded up to now for special fonts and check them, starting with the lowest font number. Note that this can sometimes lead to surprising results since the @code{fonts} line in the @file{DESC} file often contains empty positions which are filled later on. For example, consider the following: @Example fonts 3 0 0 FOO @endExample @noindent This mounts font @code{foo} at font position@tie{}3. We assume that @code{FOO} is a special font, containing glyph @code{foo}, and that no font has been loaded yet. The line @Example .fspecial BAR BAZ @endExample @noindent makes font @code{BAZ} special only if font @code{BAR} is active. We further assume that @code{BAZ} is really a special font, i.e., the font description file contains the @code{special} keyword, and that it also contains glyph @code{foo} with a special shape fitting to font @code{BAR}. After executing @code{fspecial}, font @code{BAR} is loaded at font position@tie{}1, and @code{BAZ} at position@tie{}2. We now switch to a new font @code{XXX}, trying to access glyph @code{foo} which is assumed to be missing. There are neither font-specific special fonts for @code{XXX} nor any other fonts made special with the @code{special} request, so @code{gtroff} starts the search for special fonts in the list of already mounted fonts, with increasing font positions. Consequently, it finds @code{BAZ} before @code{FOO} even for @code{XXX} which is not the intended behaviour. @end itemize @xref{Font Files}, and @ref{Special Fonts}, for more details. @cindex list of available glyphs (@cite{groff_char(7)} man page) @cindex available glyphs, list (@cite{groff_char(7)} man page) @cindex glyphs, available, list (@cite{groff_char(7)} man page) The list of available symbols is device dependent; see the @cite{groff_char(7)} man page for a complete list of all glyphs. For example, say @Example man -Tdvi groff_char > groff_char.dvi @endExample @noindent for a list using the default DVI fonts (not all versions of the @code{man} program support the @option{-T} option). If you want to use an additional macro package to change the used fonts, @code{groff} must be called directly: @Example groff -Tdvi -mec -man groff_char.7 > groff_char.dvi @endExample @cindex composite glyph names @cindex glyph names, composite @cindex groff glyph list (GGL) @cindex GGL (groff glyph list) @cindex adobe glyph list (AGL) @cindex AGL (adobe glyph list) Glyph names not listed in groff_char(7) are derived algorithmically, using a simplified version of the Adobe Glyph List (AGL) algorithm which is described in @uref{http://partners.adobe.com@//asn@//tech@//type@//unicodegn.jsp}. The (frozen) set of glyph names which can't be derived algorithmically is called @dfn{groff glyph list (GGL)}. @itemize @bullet @item A glyph for Unicode character U+@var{XXXX}[@var{X}[@var{X}]] which is not a composite character will be named @code{u@var{XXXX}@r{[}@var{X}@r{[}@var{X}@r{]]}}. @var{X} must be an uppercase hexadecimal digit. Examples: @code{u1234}, @code{u008E}, @code{u12DB8}. The largest Unicode value is 0x10FFFF. There must be at least four @code{X} digits; if necessary, add leading zeroes (after the @samp{u}). No zero padding is allowed for character codes greater than 0xFFFF. Surrogates (i.e., Unicode values greater than 0xFFFF represented with character codes from the surrogate area U+D800-U+DFFF) are not allowed too. @item A glyph representing more than a single input character will be named @display @samp{u} @var{component1} @samp{_} @var{component2} @samp{_} @var{component3} @dots{} @end display @noindent Example: @code{u0045_0302_0301}. For simplicity, all Unicode characters which are composites must be decomposed maximally (this is normalization form@tie{}D in the Unicode standard); for example, @code{u00CA_0301} is not a valid glyph name since U+00CA (@sc{latin capital letter e with circumflex}) can be further decomposed into U+0045 (@sc{latin capital letter e}) and U+0302 (@sc{combining circumflex accent}). @code{u0045_0302_0301} is thus the glyph name for U+1EBE, @sc{latin capital letter e with circumflex and acute}. @item groff maintains a table to decompose all algorithmically derived glyph names which are composites itself. For example, @code{u0100} (@sc{latin letter a with macron}) will be automatically decomposed into @code{u0041_0304}. Additionally, a glyph name of the GGL is preferred to an algorithmically derived glyph name; groff also automatically does the mapping. Example: The glyph @code{u0045_0302} will be mapped to @code{^E}. @item glyph names of the GGL can't be used in composite glyph names; for example, @code{^E_u0301} is invalid. @end itemize @DefescList {\\, @lparen{}, nm, } @DefescItem {\\, @lbrack{}, name, @rbrack} @DefescListEnd {\\, @lbrack{}, component1 component2 @dots{}, @rbrack} Insert a symbol @var{name} (two-character name @var{nm}) or a composite glyph with component glyphs @var{component1}, @var{component2}, @enddots{} There is no special syntax for one-character names -- the natural form @samp{\@var{n}} would collide with escapes.@footnote{Note that a one-character symbol is not the same as an input character, i.e., the character @code{a} is not the same as @code{\[a]}. By default, @code{groff} defines only a single one-character symbol, @code{\[-]}; it is usually accessed as @code{\-}. On the other hand, @code{gtroff} has the special feature that @code{\[char@var{XXX}]} is the same as the input character with character code @var{XXX}. For example, @code{\[char97]} is identical to the letter @code{a} if @acronym{ASCII} encoding is active.} If @var{name} is undefined, a warning of type @samp{char} is generated, and the escape is ignored. @xref{Debugging}, for information about warnings. groff resolves @code{\[...]} with more than a single component as follows: @itemize @bullet @item Any component which is found in the GGL will be converted to the @code{u@var{XXXX}} form. @item Any component @code{u@var{XXXX}} which is found in the list of decomposable glyphs will be decomposed. @item The resulting elements are then concatenated with @samp{_} inbetween, dropping the leading @samp{u} in all elements but the first. @end itemize No check for the existence of any component (similar to @code{tr} request) will be done. Examples: @table @code @item \[A ho] @samp{A} maps to @code{u0041}, @samp{ho} maps to @code{u02DB}, thus the final glyph name would be @code{u0041_02DB}. Note this is not the expected result: The ogonek glyph @samp{ho} is a spacing ogonek, but for a proper composite a non-spacing ogonek (U+0328) is necessary. Looking into the file @file{composite.tmac} one can find @w{@samp{.composite ho u0328}} which changes the mapping of @samp{ho} while a composite glyph name is constructed, causing the final glyph name to be @code{u0041_0328}. @item \[^E u0301] @itemx \[^E aa] @itemx \[E a^ aa] @itemx \[E ^ '] @samp{^E} maps to @code{u0045_0302}, thus the final glyph name is @code{u0045_0302_0301} in all forms (assuming proper calls of the @code{composite} request). @end table It is not possible to define glyphs with names like @w{@samp{A ho}} within a groff font file. This is not really a limitation; instead, you have to define @code{u0041_0328}. @endDefesc @Defesc {\\C, ', xxx, '} @cindex named character (@code{\C}) @cindex character, named (@code{\C}) Typeset the glyph named @var{xxx}.@footnote{@code{\C} is actually a misnomer since it accesses an output glyph.} Normally it is more convenient to use @code{\[@var{xxx}]}, but @code{\C} has the advantage that it is compatible with newer versions of @acronym{AT&T} @code{troff} and is available in compatibility mode. @endDefesc @Defreq {composite, from to} @pindex composite.tmac Map glyph name @var{from} to glyph name @var{to} if it is used in @code{\[...]} with more than one component. See above for examples. This mapping is based on glyph names only; no check for the existence of either glyph is done. A set of default mappings for many accents can be found in the file @file{composite.tmac} which is loaded at start-up. @endDefreq @Defesc {\\N, ', n, '} @cindex numbered glyph (@code{\N}) @cindex glyph, numbered (@code{\N}) @cindex @code{char} request, used with @code{\N} @cindex Unicode Typeset the glyph with code@tie{}@var{n} in the current font (@code{n}@tie{}is @strong{not} the input character code). The number @var{n}@tie{}can be any non-negative decimal integer. Most devices only have glyphs with codes between 0 and@tie{}255; the Unicode output device uses codes in the range 0--65535. If the current font does not contain a glyph with that code, special fonts are @emph{not} searched. The @code{\N} escape sequence can be conveniently used in conjunction with the @code{char} request: @Example .char \[phone] \f[ZD]\N'37' @endExample @noindent @pindex DESC @cindex unnamed glyphs @cindex glyphs, unnamed The code of each glyph is given in the fourth column in the font description file after the @code{charset} command. It is possible to include unnamed glyphs in the font description file by using a name of @samp{---}; the @code{\N} escape sequence is the only way to use these. No kerning is applied to glyphs accessed with @code{\N}. @endDefesc Some escape sequences directly map onto special glyphs. @Defesc {\\', , , } This is a backslash followed by the apostrophe character, @acronym{ASCII} character @code{0x27} (@acronym{EBCDIC} character @code{0x7D}). The same as @code{\[aa]}, the acute accent. @endDefesc @Defesc {\\`, , , } This is a backslash followed by @acronym{ASCII} character @code{0x60} (@acronym{EBCDIC} character @code{0x79} usually). The same as @code{\[ga]}, the grave accent. @endDefesc @Defesc {\\-, , , } This is the same as @code{\[-]}, the minus sign in the current font. @endDefesc @Defreq {cflags, n c1 c2 @dots{}} @cindex glyph properties (@code{cflags}) @cindex character properties (@code{cflags}) @cindex properties of glyphs (@code{cflags}) @cindex properties of characters (@code{cflags}) Input characters and symbols have certain properties associated with it.@footnote{Note that the output glyphs themselves don't have such properties. For @code{gtroff}, a glyph is a numbered box with a given width, depth, and height, nothing else. All manipulations with the @code{cflags} request work on the input level.} These properties can be modified with the @code{cflags} request. The first argument is the sum of the desired flags and the remaining arguments are the characters or symbols to have those properties. It is possible to omit the spaces between the characters or symbols. @table @code @item 1 @cindex end-of-sentence characters @cindex characters, end-of-sentence The character ends sentences (initially characters @samp{.?!} have this property). @item 2 @cindex hyphenating characters @cindex characters, hyphenation Lines can be broken before the character (initially no characters have this property). @item 4 @cindex @code{hy} glyph, and @code{cflags} @cindex @code{em} glyph, and @code{cflags} Lines can be broken after the character (initially the character @samp{-} and the symbols @samp{\[hy]} and @samp{\[em]} have this property). @item 8 @cindex overlapping characters @cindex characters, overlapping @cindex @code{ul} glyph, and @code{cflags} @cindex @code{rn} glyph, and @code{cflags} @cindex @code{ru} glyph, and @code{cflags} @cindex @code{radicalex} glyph, and @code{cflags} @cindex @code{sqrtex} glyph, and @code{cflags} The character overlaps horizontally if used as a horizontal line building element. Initially the symbols @samp{\[ul]}, @samp{\[rn]}, @samp{\[ru]}, @samp{\[radicalex]}, and @samp{\[sqrtex]} have this property. @item 16 @cindex @code{br} glyph, and @code{cflags} The character overlaps vertically if used as vertical line building element. Initially symbol @samp{\[br]} has this property. @item 32 @cindex transparent characters @cindex character, transparent @cindex @code{"}, at end of sentence @cindex @code{'}, at end of sentence @cindex @code{)}, at end of sentence @cindex @code{]}, at end of sentence @cindex @code{*}, at end of sentence @cindex @code{dg} glyph, at end of sentence @cindex @code{rq} glyph, at end of sentence An end-of-sentence character followed by any number of characters with this property is treated as the end of a sentence if followed by a newline or two spaces; in other words the character is @dfn{transparent} for the purposes of end-of-sentence recognition -- this is the same as having a zero space factor in @TeX{} (initially characters @samp{"')]*} and the symbols @samp{\[dg]} and @samp{\[rq]} have this property). @end table @endDefreq @DefreqList {char, g [@Var{string}]} @DefreqItem {fchar, g [@Var{string}]} @DefreqItem {fschar, f g [@Var{string}]} @DefreqListEnd {schar, g [@Var{string}]} @cindex defining character (@code{char}) @cindex defining fallback character (@code{fchar}, @code{fschar}, @code{schar}) @cindex character, defining (@code{char}) @cindex character, defining fallback (@code{fchar}, @code{fschar}, @code{schar}) @cindex fallback character, defining (@code{fchar}, @code{fschar}, @code{schar}) @cindex creating new characters (@code{char}) @cindex defining symbol (@code{char}) @cindex symbol, defining (@code{char}) @cindex defining glyph (@code{char}) @cindex glyph, defining (@code{char}) @cindex escape character, while defining glyph @cindex character, escape, while defining glyph @cindex @code{tr} request, and glyph definitions @cindex @code{cp} request, and glyph definitions @cindex @code{rc} request, and glyph definitions @cindex @code{lc} request, and glyph definitions @cindex @code{\l}, and glyph definitions @cindex @code{\L}, and glyph definitions @cindex @code{\&}, and glyph definitions @cindex @code{\e}, and glyph definitions @cindex @code{hcode} request, and glyph definitions Define a new glyph@tie{}@var{g} to be @var{string} (which can be empty).@footnote{@code{char} is a misnomer since an output glyph is defined.} Every time glyph@tie{}@var{g} needs to be printed, @var{string} is processed in a temporary environment and the result is wrapped up into a single object. Compatibility mode is turned off and the escape character is set to @samp{\} while @var{string} is being processed. Any emboldening, constant spacing or track kerning is applied to this object rather than to individual characters in @var{string}. A glyph defined by these requests can be used just like a normal glyph provided by the output device. In particular, other characters can be translated to it with the @code{tr} or @code{trin} requests; it can be made the leader character by the @code{lc} request; repeated patterns can be drawn with the glyph using the @code{\l} and @code{\L} escape sequences; words containing the glyph can be hyphenated correctly if the @code{hcode} request is used to give the glyph's symbol a hyphenation code. There is a special anti-recursion feature: Use of @code{g} within the glyph's definition is handled like normal characters and symbols not defined with @code{char}. Note that the @code{tr} and @code{trin} requests take precedence if @code{char} accesses the same symbol. @Example .tr XY X @result{} Y .char X Z X @result{} Y .tr XX X @result{} Z @endExample The @code{fchar} request defines a fallback glyph: @code{gtroff} only checks for glyphs defined with @code{fchar} if it cannot find the glyph in the current font. @code{gtroff} carries out this test before checking special fonts. @code{fschar} defines a fallback glyph for font@tie{}@var{f}: @code{gtroff} checks for glyphs defined with @code{fschar} after the list of fonts declared as font-specific special fonts with the @code{fspecial} request, but before the list of fonts declared as global special fonts with the @code{special} request. Finally, the @code{schar} request defines a global fallback glyph: @code{gtroff} checks for glyphs defined with @code{schar} after the list of fonts declared as global special fonts with the @code{special} request, but before the already mounted special fonts. @xref{Using Symbols}, for a detailed description of the glyph searching mechanism in @code{gtroff}. @endDefreq @DefreqList {rchar, c1 c2 @dots{}} @DefreqListEnd {rfschar, f c1 c2 @dots{}} @cindex removing glyph definition (@code{rchar}, @code{rfschar}) @cindex glyph, removing definition (@code{rchar}, @code{rfschar}) @cindex fallback glyph, removing definition (@code{rchar}, @code{rfschar}) Remove the definitions of glyphs @var{c1}, @var{c2},@tie{}@enddots{} This undoes the effect of a @code{char}, @code{fchar}, or @code{schar} request. It is possible to omit the whitespace between arguments. The request @code{rfschar} removes glyph definitions defined with @code{fschar} for glyph@tie{}f. @endDefreq @xref{Special Characters}. @c --------------------------------------------------------------------- @node Special Fonts, Artificial Fonts, Using Symbols, Fonts and Symbols @subsection Special Fonts @cindex special fonts @cindex fonts, special Special fonts are those that @code{gtroff} searches when it cannot find the requested glyph in the current font. The Symbol font is usually a special font. @code{gtroff} provides the following two requests to add more special fonts. @xref{Using Symbols}, for a detailed description of the glyph searching mechanism in @code{gtroff}. Usually, only non-TTY devices have special fonts. @DefreqList {special, [@Var{s1} @Var{s2} @dots{}]} @DefreqListEnd {fspecial, f [@Var{s1} @Var{s2} @dots{}]} @kindex fonts @pindex DESC Use the @code{special} request to define special fonts. Initially, this list is empty. Use the @code{fspecial} request to designate special fonts only when font@tie{}@var{f} is active. Initially, this list is empty. Previous calls to @code{special} or @code{fspecial} are overwritten; without arguments, the particular list of special fonts is set to empty. Special fonts are searched in the order they appear as arguments. All fonts which appear in a call to @code{special} or @code{fspecial} are loaded. @xref{Using Symbols}, for the exact search order of glyphs. @endDefreq @c --------------------------------------------------------------------- @node Artificial Fonts, Ligatures and Kerning, Special Fonts, Fonts and Symbols @subsection Artificial Fonts @cindex artificial fonts @cindex fonts, artificial There are a number of requests and escapes for artificially creating fonts. These are largely vestiges of the days when output devices did not have a wide variety of fonts, and when @code{nroff} and @code{troff} were separate programs. Most of them are no longer necessary in GNU @code{troff}. Nevertheless, they are supported. @DefescList {\\H, ', height, '} @DefescItem {\\H, ', @t{+}height, '} @DefescItem {\\H, ', @t{-}height, '} @DefregListEnd {.height} @cindex changing the font height (@code{\H}) @cindex font height, changing (@code{\H}) @cindex height, font, changing (@code{\H}) Change (increment, decrement) the height of the current font, but not the width. If @var{height} is zero, restore the original height. Default scaling indicator is @samp{z}. The read-only number register @code{.height} contains the font height as set by @code{\H}. Currently, only the @option{-Tps} device supports this feature. Note that @code{\H} doesn't produce an input token in @code{gtroff}. As a consequence, it can be used in requests like @code{mc} (which expects a single character as an argument) to change the font on the fly: @Example .mc \H'+5z'x\H'0' @endExample In compatibility mode, @code{gtroff} behaves differently: If an increment or decrement is used, it is always taken relative to the current point size and not relative to the previously selected font height. Thus, @Example .cp 1 \H'+5'test \H'+5'test @endExample @noindent prints the word @samp{test} twice with the same font height (five points larger than the current font size). @endDefesc @DefescList {\\S, ', slant, '} @DefregListEnd {.slant} @cindex changing the font slant (@code{\S}) @cindex font slant, changing (@code{\S}) @cindex slant, font, changing (@code{\S}) Slant the current font by @var{slant} degrees. Positive values slant to the right. Only integer values are possible. The read-only number register @code{.slant} contains the font slant as set by @code{\S}. Currently, only the @option{-Tps} device supports this feature. Note that @code{\S} doesn't produce an input token in @code{gtroff}. As a consequence, it can be used in requests like @code{mc} (which expects a single character as an argument) to change the font on the fly: @Example .mc \S'20'x\S'0' @endExample This request is incorrectly documented in the original @acronym{UNIX} troff manual; the slant is always set to an absolute value. @endDefesc @Defreq {ul, [@Var{lines}]} @cindex underlining (@code{ul}) The @code{ul} request normally underlines subsequent lines if a TTY output device is used. Otherwise, the lines are printed in italics (only the term `underlined' is used in the following). The single argument is the number of input lines to be underlined; with no argument, the next line is underlined. If @var{lines} is zero or negative, stop the effects of @code{ul} (if it was active). Requests and empty lines do not count for computing the number of underlined input lines, even if they produce some output like @code{tl}. Lines inserted by macros (e.g.@: invoked by a trap) do count. At the beginning of @code{ul}, the current font is stored and the underline font is activated. Within the span of a @code{ul} request, it is possible to change fonts, but after the last line affected by @code{ul} the saved font is restored. This number of lines still to be underlined is associated with the current environment (@pxref{Environments}). The underline font can be changed with the @code{uf} request. @c XXX @xref should be changed to grotty @c @xref{Troff and Nroff Mode}, for a discussion how underlining is @c implemented in for TTY output devices, and which problems can arise. The @code{ul} request does not underline spaces. @endDefreq @Defreq {cu, [@Var{lines}]} @cindex continuous underlining (@code{cu}) @cindex underlining, continuous (@code{cu}) The @code{cu} request is similar to @code{ul} but underlines spaces as well (if a TTY output device is used). @endDefreq @Defreq {uf, font} @cindex underline font (@code{uf}) @cindex font for underlining (@code{uf}) Set the underline font (globally) used by @code{ul} and @code{cu}. By default, this is the font at position@tie{}2. @var{font} can be either a non-negative font position or the name of a font. @endDefreq @DefreqList {bd, font [@Var{offset}]} @DefreqItem {bd, font1 font2 [@Var{offset}]} @DefregListEnd {.b} @cindex imitating bold face (@code{bd}) @cindex bold face, imitating (@code{bd}) Artificially create a bold font by printing each glyph twice, slightly offset. Two syntax forms are available. @itemize @bullet @item Imitate a bold font unconditionally. The first argument specifies the font to embolden, and the second is the number of basic units, minus one, by which the two glyphs are offset. If the second argument is missing, emboldening is turned off. @var{font} can be either a non-negative font position or the name of a font. @var{offset} is available in the @code{.b} read-only register if a special font is active; in the @code{bd} request, its default unit is @samp{u}. @cindex @code{fspecial} request, and imitating bold @kindex special @cindex embolding of special fonts @cindex special fonts, emboldening @item Imitate a bold form conditionally. Embolden @var{font1} by @var{offset} only if font @var{font2} is the current font. This command can be issued repeatedly to set up different emboldening values for different current fonts. If the second argument is missing, emboldening is turned off for this particular current font. This affects special fonts only (either set up with the @code{special} command in font files or with the @code{fspecial} request). @end itemize @endDefreq @Defreq {cs, font [@Var{width} [@Var{em-size}]]} @cindex constant glyph space mode (@code{cs}) @cindex mode for constant glyph space (@code{cs}) @cindex glyph, constant space @cindex @code{ps} request, and constant glyph space mode Switch to and from @dfn{constant glyph space mode}. If activated, the width of every glyph is @math{@var{width}/36} ems. The em size is given absolutely by @var{em-size}; if this argument is missing, the em value is taken from the current font size (as set with the @code{ps} request) when the font is effectively in use. Without second and third argument, constant glyph space mode is deactivated. Default scaling indicator for @var{em-size} is @samp{z}; @var{width} is an integer. @endDefreq @c --------------------------------------------------------------------- @node Ligatures and Kerning, , Artificial Fonts, Fonts and Symbols @subsection Ligatures and Kerning @cindex ligatures and kerning @cindex kerning and ligatures Ligatures are groups of characters that are run together, i.e, producing a single glyph. For example, the letters `f' and `i' can form a ligature `fi' as in the word `file'. This produces a cleaner look (albeit subtle) to the printed output. Usually, ligatures are not available in fonts for TTY output devices. Most @sc{PostScript} fonts support the fi and fl ligatures. The C/A/T typesetter that was the target of @acronym{AT&T} @code{troff} also supported `ff', `ffi', and `ffl' ligatures. Advanced typesetters or `expert' fonts may include ligatures for `ft' and `ct', although GNU @code{troff} does not support these (yet). Only the current font is checked for ligatures and kerns; neither special fonts nor entities defined with the @code{char} request (and its siblings) are taken into account. @DefreqList {lg, [@Var{flag}]} @DefregListEnd {.lg} @cindex activating ligatures (@code{lg}) @cindex ligatures, activating (@code{lg}) @cindex ligatures enabled register (@code{.lg}) Switch the ligature mechanism on or off; if the parameter is non-zero or missing, ligatures are enabled, otherwise disabled. Default is on. The current ligature mode can be found in the read-only number register @code{.lg} (set to 1 or@tie{}2 if ligatures are enabled, 0@tie{}otherwise). Setting the ligature mode to@tie{}2 enables the two-character ligatures (fi, fl, and ff) and disables the three-character ligatures (ffi and ffl). @endDefreq @dfn{Pairwise kerning} is another subtle typesetting mechanism that modifies the distance between a glyph pair to improve readability. In most cases (but not always) the distance is decreased. @ifnotinfo For example, compare the combination of the letters `V' and `A'. With kerning, `VA' is printed. Without kerning it appears as `V@w{}A'. @end ifnotinfo Typewriter-like fonts and fonts for terminals where all glyphs have the same width don't use kerning. @DefreqList {kern, [@Var{flag}]} @DefregListEnd {.kern} @cindex activating kerning (@code{kern}) @cindex kerning, activating (@code{kern}) @cindex kerning enabled register (@code{.kern}) Switch kerning on or off. If the parameter is non-zero or missing, enable pairwise kerning, otherwise disable it. The read-only number register @code{.kern} is set to@tie{}1 if pairwise kerning is enabled, 0@tie{}otherwise. @cindex zero width space character (@code{\&}) @cindex character, zero width space (@code{\&}) @cindex space character, zero width (@code{\&}) If the font description file contains pairwise kerning information, glyphs from that font are kerned. Kerning between two glyphs can be inhibited by placing @code{\&} between them: @samp{V\&A}. @xref{Font File Format}. @endDefreq @cindex track kerning @cindex kerning, track @dfn{Track kerning} expands or reduces the space between glyphs. This can be handy, for example, if you need to squeeze a long word onto a single line or spread some text to fill a narrow column. It must be used with great care since it is usually considered bad typography if the reader notices the effect. @Defreq {tkf, f s1 n1 s2 n2} @cindex activating track kerning (@code{tkf}) @cindex track kerning, activating (@code{tkf}) Enable track kerning for font@tie{}@var{f}. If the current font is@tie{}@var{f} the width of every glyph is increased by an amount between @var{n1} and @var{n2} (@var{n1}, @var{n2} can be negative); if the current point size is less than or equal to @var{s1} the width is increased by @var{n1}; if it is greater than or equal to @var{s2} the width is increased by @var{n2}; if the point size is greater than or equal to @var{s1} and less than or equal to @var{s2} the increase in width is a linear function of the point size. The default scaling indicator is @samp{z} for @var{s1} and @var{s2}, @samp{p} for @var{n1} and @var{n2}. Note that the track kerning amount is added even to the rightmost glyph in a line; for large values it is thus recommended to increase the line length by the same amount to compensate it. @endDefreq Sometimes, when typesetting letters of different fonts, more or less space at such boundaries are needed. There are two escapes to help with this. @Defesc {\\/, , , } @cindex italic correction (@code{\/}) @cindex correction, italic (@code{\/}) @cindex correction between italic and roman glyph (@code{\/}, @code{\,}) @cindex roman glyph, correction after italic glyph (@code{\/}) @cindex italic glyph, correction before roman glyph (@code{\/}) @cindex glyph, italic correction (@code{\/}) Increase the width of the preceding glyph so that the spacing between that glyph and the following glyph is correct if the following glyph is a roman glyph. For example, if an italic@tie{}@code{f} is immediately followed by a roman right parenthesis, then in many fonts the top right portion of the@tie{}@code{f} overlaps the top left of the right parenthesis. Use this escape sequence whenever an italic glyph is immediately followed by a roman glyph without any intervening space. This small amount of space is also called @dfn{italic correction}. @iftex @example @group \f[I]f\f[R]) @result{} {@it f}@r{)} \f[I]f\/\f[R]) @result{} @i{f}@r{)} @end group @end example @end iftex @endDefesc @Defesc {\\\,, , , } @cindex left italic correction (@code{\,}) @cindex correction, left italic (@code{\,}) @cindex glyph, left italic correction (@code{\,}) @cindex roman glyph, correction before italic glyph (@code{\,}) @cindex italic glyph, correction after roman glyph (@code{\,}) Modify the spacing of the following glyph so that the spacing between that glyph and the preceding glyph is correct if the preceding glyph is a roman glyph. Use this escape sequence whenever a roman glyph is immediately followed by an italic glyph without any intervening space. In analogy to above, this space could be called @dfn{left italic correction}, but this term isn't used widely. @iftex @example @group q\f[I]f @result{} @r{q}@i{f} q\,\f[I]f @result{} @r{q}@math{@ptexcomma}@i{f} @end group @end example @end iftex @endDefesc @Defesc {\\&, , , } Insert a zero-width character, which is invisible. Its intended use is to stop interaction of a character with its surrounding. @itemize @bullet @item It prevents the insertion of extra space after an end-of-sentence character. @Example Test. Test. @result{} Test. Test. Test.\& Test. @result{} Test. Test. @endExample @item It prevents interpretation of a control character at the beginning of an input line. @Example .Test @result{} warning: `Test' not defined \&.Test @result{} .Test @endExample @item It prevents kerning between two glyphs. @ifnotinfo @example @group VA @result{} @r{VA} V\&A @result{} @r{V@w{}A} @end group @end example @end ifnotinfo @item It is needed to map an arbitrary character to nothing in the @code{tr} request (@pxref{Character Translations}). @end itemize @endDefesc @Defesc {\\), , , } This escape is similar to @code{\&} except that it behaves like a character declared with the @code{cflags} request to be transparent for the purposes of an end-of-sentence character. Its main usage is in macro definitions to protect against arguments starting with a control character. @Example .de xxx \)\\$1 .. .de yyy \&\\$1 .. This is a test.\c .xxx ' This is a test. @result{}This is a test.' This is a test. This is a test.\c .yyy ' This is a test. @result{}This is a test.' This is a test. @endExample @endDefesc @c ===================================================================== @node Sizes, Strings, Fonts and Symbols, gtroff Reference @section Sizes @cindex sizes @cindex baseline @cindex type size @cindex size of type @cindex vertical spacing @cindex spacing, vertical @code{gtroff} uses two dimensions with each line of text, type size and vertical spacing. The @dfn{type size} is approximately the height of the tallest glyph.@footnote{This is usually the parenthesis. Note that in most cases the real dimensions of the glyphs in a font are @emph{not} related to its type size! For example, the standard @sc{PostScript} font families `Times Roman', `Helvetica', and `Courier' can't be used together at 10@dmn{pt}; to get acceptable output, the size of `Helvetica' has to be reduced by one point, and the size of `Courier' must be increased by one point.} @dfn{Vertical spacing} is the amount of space @code{gtroff} allows for a line of text; normally, this is about 20%@tie{}larger than the current type size. Ratios smaller than this can result in hard-to-read text; larger than this, it spreads the text out more vertically (useful for term papers). By default, @code{gtroff} uses 10@tie{}point type on 12@tie{}point spacing. @cindex leading The difference between type size and vertical spacing is known, by typesetters, as @dfn{leading} (this is pronounced `ledding'). @menu * Changing Type Sizes:: * Fractional Type Sizes:: @end menu @c --------------------------------------------------------------------- @node Changing Type Sizes, Fractional Type Sizes, Sizes, Sizes @subsection Changing Type Sizes @DefreqList {ps, [@Var{size}]} @DefreqItem {ps, @t{+}@Var{size}} @DefreqItem {ps, @t{-}@Var{size}} @DefescItem {\\s, , size, } @DefregListEnd {.s} @cindex changing type sizes (@code{ps}, @code{\s}) @cindex type sizes, changing (@code{ps}, @code{\s}) @cindex point sizes, changing (@code{ps}, @code{\s}) Use the @code{ps} request or the @code{\s} escape to change (increase, decrease) the type size (in points). Specify @var{size} as either an absolute point size, or as a relative change from the current size. The size@tie{}0, or no argument, goes back to the previous size. Default scaling indicator of @code{size} is @samp{z}. If @code{size} is zero or negative, it is set to 1@dmn{u}. @cindex type size registers (@code{.s}, @code{.ps}) @cindex point size registers (@code{.s}, @code{.ps}) The read-only number register @code{.s} returns the point size in points as a decimal fraction. This is a string. To get the point size in scaled points, use the @code{.ps} register instead. @code{.s} is associated with the current environment (@pxref{Environments}). @Example snap, snap, .ps +2 grin, grin, .ps +2 wink, wink, \s+2nudge, nudge,\s+8 say no more! .ps 10 @endExample The @code{\s} escape may be called in a variety of ways. Much like other escapes there must be a way to determine where the argument ends and the text begins. Any of the following forms are valid: @table @code @item \s@var{n} Set the point size to @var{n}@tie{}points. @var{n}@tie{}must be either 0 or in the range 4 to@tie{}39. @item \s+@var{n} @itemx \s-@var{n} Increase or decrease the point size by @var{n}@tie{}points. @var{n}@tie{}must be exactly one digit. @item \s(@var{nn} Set the point size to @var{nn}@tie{}points. @var{nn} must be exactly two digits. @item \s+(@var{nn} @itemx \s-(@var{nn} @itemx \s(+@var{nn} @itemx \s(-@var{nn} Increase or decrease the point size by @var{nn}@tie{}points. @var{nn} must be exactly two digits. @end table Note that @code{\s} doesn't produce an input token in @code{gtroff}. As a consequence, it can be used in requests like @code{mc} (which expects a single character as an argument) to change the font on the fly: @Example .mc \s[20]x\s[0] @endExample @xref{Fractional Type Sizes}, for yet another syntactical form of using the @code{\s} escape. @endDefreq @Defreq {sizes, s1 s2 @dots{} sn [0]} Some devices may only have certain permissible sizes, in which case @code{gtroff} rounds to the nearest permissible size. The @file{DESC} file specifies which sizes are permissible for the device. Use the @code{sizes} request to change the permissible sizes for the current output device. Arguments are in scaled points; the @code{sizescale} line in the @file{DESC} file for the output device provides the scaling factor. For example, if the scaling factor is 1000, then the value 12000 is 12@tie{}points. Each argument can be a single point size (such as @samp{12000}), or a range of sizes (such as @samp{4000-72000}). You can optionally end the list with a zero. @endDefreq @DefreqList {vs, [@Var{space}]} @DefreqItem {vs, @t{+}@Var{space}} @DefreqItem {vs, @t{-}@Var{space}} @DefregListEnd {.v} @cindex changing vertical line spacing (@code{vs}) @cindex vertical line spacing, changing (@code{vs}) @cindex vertical line spacing register (@code{.v}) Change (increase, decrease) the vertical spacing by @var{space}. The default scaling indicator is @samp{p}. If @code{vs} is called without an argument, the vertical spacing is reset to the previous value before the last call to @code{vs}. @cindex @code{.V} register, and @code{vs} @code{gtroff} creates a warning of type @samp{range} if @var{space} is negative; the vertical spacing is then set to smallest positive value, the vertical resolution (as given in the @code{.V} register). Note that @w{@samp{.vs 0}} isn't saved in a diversion since it doesn't result in a vertical motion. You explicitly have to repeat this command before inserting the diversion. The read-only number register @code{.v} contains the current vertical spacing; it is associated with the current environment (@pxref{Environments}). @endDefreq @cindex vertical line spacing, effective value The effective vertical line spacing consists of four components. Breaking a line causes the following actions (in the given order). @itemize @bullet @item @cindex extra pre-vertical line space (@code{\x}) @cindex line space, extra pre-vertical (@code{\x}) Move the current point vertically by the @dfn{extra pre-vertical line space}. This is the minimum value of all @code{\x} escapes with a negative argument in the current output line. @item Move the current point vertically by the vertical line spacing as set with the @code{vs} request. @item Output the current line. @item @cindex extra post-vertical line space (@code{\x}) @cindex line space, extra post-vertical (@code{\x}) Move the current point vertically by the @dfn{extra post-vertical line space}. This is the maximum value of all @code{\x} escapes with a positive argument in the line which has just been output. @item @cindex post-vertical line spacing @cindex line spacing, post-vertical (@code{pvs}) Move the current point vertically by the @dfn{post-vertical line spacing} as set with the @code{pvs} request. @end itemize @cindex double-spacing (@code{vs}, @code{pvs}) It is usually better to use @code{vs} or @code{pvs} instead of @code{ls} to produce double-spaced documents: @code{vs} and @code{pvs} have a finer granularity for the inserted vertical space compared to @code{ls}; furthermore, certain preprocessors assume single-spacing. @xref{Manipulating Spacing}, for more details on the @code{\x} escape and the @code{ls} request. @DefreqList {pvs, [@Var{space}]} @DefreqItem {pvs, @t{+}@Var{space}} @DefreqItem {pvs, @t{-}@Var{space}} @DefregListEnd {.pvs} @cindex @code{ls} request, alternative to (@code{pvs}) @cindex post-vertical line spacing, changing (@code{pvs}) @cindex post-vertical line spacing register (@code{.pvs}) Change (increase, decrease) the post-vertical spacing by @var{space}. The default scaling indicator is @samp{p}. If @code{pvs} is called without an argument, the post-vertical spacing is reset to the previous value before the last call to @code{pvs}. @code{gtroff} creates a warning of type @samp{range} if @var{space} is zero or negative; the vertical spacing is then set to zero. The read-only number register @code{.pvs} contains the current post-vertical spacing; it is associated with the current environment (@pxref{Environments}). @endDefreq @c --------------------------------------------------------------------- @node Fractional Type Sizes, , Changing Type Sizes, Sizes @subsection Fractional Type Sizes @cindex fractional type sizes @cindex fractional point sizes @cindex type sizes, fractional @cindex point sizes, fractional @cindex sizes, fractional @cindex @code{s} unit @cindex unit, @code{s} @cindex @code{z} unit @cindex unit, @code{z} @cindex @code{ps} request, with fractional type sizes @cindex @code{cs} request, with fractional type sizes @cindex @code{tkf} request, with fractional type sizes @cindex @code{\H}, with fractional type sizes @cindex @code{\s}, with fractional type sizes A @dfn{scaled point} is equal to @math{1/@var{sizescale}} points, where @var{sizescale} is specified in the @file{DESC} file (1@tie{}by default). There is a new scale indicator @samp{z} which has the effect of multiplying by @var{sizescale}. Requests and escape sequences in @code{gtroff} interpret arguments that represent a point size as being in units of scaled points, but they evaluate each such argument using a default scale indicator of @samp{z}. Arguments treated in this way are the argument to the @code{ps} request, the third argument to the @code{cs} request, the second and fourth arguments to the @code{tkf} request, the argument to the @code{\H} escape sequence, and those variants of the @code{\s} escape sequence that take a numeric expression as their argument (see below). For example, suppose @var{sizescale} is@tie{}1000; then a scaled point is equivalent to a millipoint; the request @w{@samp{.ps 10.25}} is equivalent to @w{@samp{.ps 10.25z}} and thus sets the point size to 10250@tie{}scaled points, which is equal to 10.25@tie{}points. @code{gtroff} disallows the use of the @samp{z} scale indicator in instances where it would make no sense, such as a numeric expression whose default scale indicator was neither @samp{u} nor @samp{z}. Similarly it would make no sense to use a scaling indicator other than @samp{z} or @samp{u} in a numeric expression whose default scale indicator was @samp{z}, and so @code{gtroff} disallows this as well. There is also new scale indicator @samp{s} which multiplies by the number of units in a scaled point. So, for example, @samp{\n[.ps]s} is equal to @samp{1m}. Be sure not to confuse the @samp{s} and @samp{z} scale indicators. @Defreg {.ps} A read-only number register returning the point size in scaled points. @code{.ps} is associated with the current environment (@pxref{Environments}). @endDefreg @DefregList {.psr} @DefregListEnd {.sr} @cindex last-requested point size registers (@code{.psr}, @code{.sr}) @cindex point size registers, last-requested (@code{.psr}, @code{.sr}) @cindex @code{.ps} register, in comparison with @code{.psr} @cindex @code{.s} register, in comparison with @code{.sr} The last-requested point size in scaled points is contained in the @code{.psr} read-only number register. The last requested point size in points as a decimal fraction can be found in @code{.sr}. This is a string-valued read-only number register. Note that the requested point sizes are device-independent, whereas the values returned by the @code{.ps} and @code{.s} registers are not. For example, if a point size of 11@dmn{pt} is requested, and a @code{sizes} request (or a @code{sizescale} line in a @file{DESC} file) specifies 10.95@dmn{pt} instead, this value is actually used. Both registers are associated with the current environment (@pxref{Environments}). @endDefreg The @code{\s} escape has the following syntax for working with fractional type sizes: @table @code @item \s[@var{n}] @itemx \s'@var{n}' Set the point size to @var{n}@tie{}scaled points; @var{n}@tie{}is a numeric expression with a default scale indicator of @samp{z}. @item \s[+@var{n}] @itemx \s[-@var{n}] @itemx \s+[@var{n}] @itemx \s-[@var{n}] @itemx \s'+@var{n}' @itemx \s'-@var{n}' @itemx \s+'@var{n}' @itemx \s-'@var{n}' Increase or or decrease the point size by @var{n}@tie{}scaled points; @var{n}@tie{}is a numeric expression with a default scale indicator of @samp{z}. @end table @xref{Font Files}. @c ===================================================================== @node Strings, Conditionals and Loops, Sizes, gtroff Reference @section Strings @cindex strings @code{gtroff} has string variables, which are entirely for user convenience (i.e.@: there are no built-in strings exept @code{.T}, but even this is a read-write string variable). @DefreqList {ds, name [@Var{string}]} @DefreqItem {ds1, name [@Var{string}]} @DefescItem {\\*, , n, } @DefescItem {\\*, @lparen{}, nm, } @DefescListEnd {\\*, @lbrack{}, name arg1 arg2 @dots{}, @rbrack{}} @cindex string interpolation (@code{\*}) @cindex string expansion (@code{\*}) @cindex interpolation of strings (@code{\*}) @cindex expansion of strings (@code{\*}) @cindex string arguments @cindex arguments, of strings Define and access a string variable @var{name} (one-character name@tie{}@var{n}, two-character name @var{nm}). If @var{name} already exists, @code{ds} overwrites the previous definition. Only the syntax form using brackets can take arguments which are handled identically to macro arguments; the single exception is that a closing bracket as an argument must be enclosed in double quotes. @xref{Request and Macro Arguments}, and @ref{Parameters}. Example: @Example .ds foo a \\$1 test . This is \*[foo nice]. @result{} This is a nice test. @endExample The @code{\*} escape @dfn{interpolates} (expands in-place) a previously-defined string variable. To be more precise, the stored string is pushed onto the input stack which is then parsed by @code{gtroff}. Similar to number registers, it is possible to nest strings, i.e. string variables can be called within string variables. If the string named by the @code{\*} escape does not exist, it is defined as empty, and a warning of type @samp{mac} is emitted (see @ref{Debugging}, for more details). @cindex comments, with @code{ds} @cindex @code{ds} request, and comments @strong{Caution:} Unlike other requests, the second argument to the @code{ds} request takes up the entire line including trailing spaces. This means that comments on a line with such a request can introduce unwanted space into a string. @Example .ds UX \s-1UNIX\s0\u\s-3tm\s0\d \" UNIX trademark @endExample @noindent Instead the comment should be put on another line or have the comment escape adjacent with the end of the string. @Example .ds UX \s-1UNIX\s0\u\s-3tm\s0\d\" UNIX trademark @endExample @cindex trailing quotes @cindex quotes, trailing @cindex leading spaces with @code{ds} @cindex spaces with @code{ds} @cindex @code{ds} request, and leading spaces To produce leading space the string can be started with a double quote. No trailing quote is needed; in fact, any trailing quote is included in your string. @Example .ds sign " Yours in a white wine sauce, @endExample @cindex multi-line strings @cindex strings, multi-line @cindex newline character, in strings, escaping @cindex escaping newline characters, in strings Strings are not limited to a single line of text. A string can span several lines by escaping the newlines with a backslash. The resulting string is stored @emph{without} the newlines. @Example .ds foo lots and lots \ of text are on these \ next several lines @endExample It is not possible to have real newlines in a string. To put a single double quote character into a string, use two consecutive double quote characters. The @code{ds1} request turns off compatibility mode while interpreting a string. To be more precise, a @dfn{compatibility save} input token is inserted at the beginning of the string, and a @dfn{compatibility restore} input token at the end. @Example .nr xxx 12345 .ds aa The value of xxx is \\n[xxx]. .ds1 bb The value of xxx ix \\n[xxx]. . .cp 1 . \*(aa @result{} warning: number register `[' not defined @result{} The value of xxx is 0xxx]. \*(bb @result{} The value of xxx ix 12345. @endExample @cindex name space, common, of macros, diversions, and strings @cindex common name space of macros, diversions, and strings @cindex macros, shared name space with strings and diversions @cindex strings, shared name space with macros and diversions @cindex diversions, shared name space with macros and strings Strings, macros, and diversions (and boxes) share the same name space. Internally, even the same mechanism is used to store them. This has some interesting consequences. For example, it is possible to call a macro with string syntax and vice versa. @Example .de xxx a funny test. .. This is \*[xxx] @result{} This is a funny test. .ds yyy a funny test This is .yyy @result{} This is a funny test. @endExample Diversions and boxes can be also called with string syntax. Another consequence is that you can copy one-line diversions or boxes to a string. @Example .di xxx a \fItest\fR .br .di .ds yyy This is \*[xxx]\c \*[yyy]. @result{} @r{This is a }@i{test}. @endExample @noindent As the previous example shows, it is possible to store formatted output in strings. The @code{\c} escape prevents the insertion of an additional blank line in the output. Copying diversions longer than a single output line produces unexpected results. @Example .di xxx a funny .br test .br .di .ds yyy This is \*[xxx]\c \*[yyy]. @result{} test This is a funny. @endExample Usually, it is not predictable whether a diversion contains one or more output lines, so this mechanism should be avoided. With @acronym{UNIX} @code{troff}, this was the only solution to strip off a final newline from a diversion. Another disadvantage is that the spaces in the copied string are already formatted, making them unstretchable. This can cause ugly results. @cindex stripping final newline in diversions @cindex diversion, stripping final newline @cindex final newline, stripping in diversions @cindex newline, final, stripping in diversions @cindex horizontal space, unformatting @cindex space, horizontal, unformatting @cindex unformatting horizontal space A clean solution to this problem is available in GNU @code{troff}, using the requests @code{chop} to remove the final newline of a diversion, and @code{unformat} to make the horizontal spaces stretchable again. @Example .box xxx a funny .br test .br .box .chop xxx .unformat xxx This is \*[xxx]. @result{} This is a funny test. @endExample @xref{Gtroff Internals}, for more information. @endDefreq @DefreqList {as, name [@Var{string}]} @DefreqListEnd {as1, name [@Var{string}]} @cindex appending to a string (@code{as}) @cindex string, appending (@code{as}) The @code{as} request is similar to @code{ds} but appends @var{string} to the string stored as @var{name} instead of redefining it. If @var{name} doesn't exist yet, it is created. @Example .as sign " with shallots, onions and garlic, @endExample The @code{as1} request is similar to @code{as}, but compatibility mode is switched off while the appended string is interpreted. To be more precise, a @dfn{compatibility save} input token is inserted at the beginning of the appended string, and a @dfn{compatibility restore} input token at the end. @endDefreq Rudimentary string manipulation routines are given with the next two requests. @Defreq {substring, str n1 [@Var{n2}]} @cindex substring (@code{substring}) Replace the string named @var{str} with the substring defined by the indices @var{n1} and@tie{}@var{n2}. The first character in the string has index@tie{}0. If @var{n2} is omitted, it is taken to be equal to the string's length. If the index value @var{n1} or @var{n2} is negative, it is counted from the end of the string, going backwards: The last character has index@tie{}@minus{}1, the character before the last character has index@tie{}@minus{}2, etc. @Example .ds xxx abcdefgh .substring xxx 1 -4 \*[xxx] @result{} bcde @endExample @endDefreq @Defreq {length, reg str} @cindex length of a string (@code{length}) @cindex string, length of (@code{length}) Compute the number of characters of @var{str} and return it in the number register @var{reg}. If @var{reg} doesn't exist, it is created. @code{str} is read in copy mode. @Example .ds xxx abcd\h'3i'efgh .length yyy \*[xxx] \n[yyy] @result{} 14 @endExample @endDefreq @Defreq {rn, xx yy} @cindex renaming request (@code{rn}) @cindex request, renaming (@code{rn}) @cindex renaming macro (@code{rn}) @cindex macro, renaming (@code{rn}) @cindex renaming string (@code{rn}) @cindex string, renaming (@code{rn}) @cindex renaming diversion (@code{rn}) @cindex diversion, renaming (@code{rn}) Rename the request, macro, diversion, or string @var{xx} to @var{yy}. @endDefreq @Defreq {rm, xx} @cindex removing request (@code{rm}) @cindex request, removing (@code{rm}) @cindex removing macro (@code{rm}) @cindex macro, removing (@code{rm}) @cindex removing string (@code{rm}) @cindex string, removing (@code{rm}) @cindex removing diversion (@code{rm}) @cindex diversion, removing (@code{rm}) Remove the request, macro, diversion, or string @var{xx}. @code{gtroff} treats subsequent invocations as if the object had never been defined. @endDefreq @Defreq {als, new old} @cindex alias, string, creating (@code{als}) @cindex alias, macro, creating (@code{als}) @cindex alias, diversion, creating (@code{als}) @cindex creating alias, for string (@code{als}) @cindex creating alias, for macro (@code{als}) @cindex creating alias, for diversion (@code{als}) @cindex string, creating alias (@code{als}) @cindex macro, creating alias (@code{als}) @cindex diversion, creating alias (@code{als}) Create an alias named @var{new} for the request, string, macro, or diversion object named @var{old}. The new name and the old name are exactly equivalent (it is similar to a hard rather than a soft link). If @var{old} is undefined, @code{gtroff} generates a warning of type @samp{mac} and ignores the request. @endDefreq @Defreq {chop, xx} Remove (chop) the last character from the macro, string, or diversion named @var{xx}. This is useful for removing the newline from the end of diversions that are to be interpolated as strings. This command can be used repeatedly; see @ref{Gtroff Internals}, for details on nodes inserted additionally by @code{gtroff}. @endDefreq @xref{Identifiers}, and @ref{Comments}. @c ===================================================================== @node Conditionals and Loops, Writing Macros, Strings, gtroff Reference @section Conditionals and Loops @cindex conditionals and loops @cindex loops and conditionals @menu * Operators in Conditionals:: * if-else:: * while:: @end menu @c --------------------------------------------------------------------- @node Operators in Conditionals, if-else, Conditionals and Loops, Conditionals and Loops @subsection Operators in Conditionals @cindex @code{if} request, operators to use with @cindex @code{while} request, operators to use with In @code{if} and @code{while} requests, there are several more operators available: @table @code @item e @itemx o True if the current page is even or odd numbered (respectively). @item n True if the document is being processed in nroff mode (i.e., the @code{.nroff} command has been issued). @item t True if the document is being processed in troff mode (i.e., the @code{.troff} command has been issued). @item v Always false. This condition is for compatibility with other @code{troff} versions only (identifying a @code{-Tversatec} device). @item '@var{xxx}'@var{yyy}' True if the string @var{xxx} is equal to the string @var{yyy}. Other characters can be used in place of the single quotes; the same set of delimiters as for the @code{\D} escape is used (@pxref{Escapes}). @code{gtroff} formats the strings before being compared: @Example .ie "|"\fR|\fP" \ true .el \ false @result{} true @endExample @noindent The resulting motions, glyph sizes, and fonts have to match,@footnote{The created output nodes must be identical. @xref{Gtroff Internals}.} and not the individual motion, size, and font requests. In the previous example, @samp{|} and @samp{\fR|\fP} both result in a roman @samp{|} glyph with the same point size and at the same location on the page, so the strings are equal. If @samp{.ft@tie{}I} had been added before the @samp{.ie}, the result would be ``false'' because (the first) @samp{|} produces an italic @samp{|} rather than a roman one. @item r @var{xxx} True if there is a number register named @var{xxx}. @item d @var{xxx} True if there is a string, macro, diversion, or request named @var{xxx}. @item m @var{xxx} True if there is a color named @var{xxx}. @item c @var{g} True if there is a glyph @var{g} available@footnote{The name of this conditional operator is a misnomer since it tests names of output glyphs.}; @var{g} is either an @acronym{ASCII} character or a special character (@code{\(@var{gg}} or @code{\[@var{ggg}]}); the condition is also true if @var{g} has been defined by the @code{char} request. @end table Note that these operators can't be combined with other operators like @samp{:} or @samp{&}; only a leading @samp{!} (without whitespace between the exclamation mark and the operator) can be used to negate the result. @Example .nr xxx 1 .ie !r xxx \ true .el \ false @result{} false @endExample A whitespace after @samp{!} always evaluates to zero (this bizarre behaviour is due to compatibility with @acronym{UNIX} @code{troff}). @Example .nr xxx 1 .ie ! r xxx \ true .el \ false @result{} r xxx true @endExample It is possible to omit the whitespace before the argument to the @samp{r}, @samp{d}, and @samp{c} operators. @xref{Expressions}. @c --------------------------------------------------------------------- @node if-else, while, Operators in Conditionals, Conditionals and Loops @subsection if-else @cindex if-else @code{gtroff} has if-then-else constructs like other languages, although the formatting can be painful. @Defreq {if, expr anything} Evaluate the expression @var{expr}, and executes @var{anything} (the remainder of the line) if @var{expr} evaluates to a value greater than zero (true). @var{anything} is interpreted as though it was on a line by itself (except that leading spaces are swallowed). @xref{Expressions}, for more info. @Example .nr xxx 1 .nr yyy 2 .if ((\n[xxx] == 1) & (\n[yyy] == 2)) true @result{} true @endExample @endDefreq @Defreq{nop, anything} Executes @var{anything}. This is similar to @code{.if@tie{}1}. @endDefreq @DefreqList {ie, expr anything} @DefreqListEnd {el, anything} Use the @code{ie} and @code{el} requests to write an if-then-else. The first request is the `if' part and the latter is the `else' part. @Example .ie n .ls 2 \" double-spacing in nroff .el .ls 1 \" single-spacing in troff @endExample @endDefreq @c there is a bug in makeinfo <= 4.1a: you can't have `@{' as an argument @c to @deffn @c @c and in 4.2 you still can't use @{ in macros. @c @DefescList {\@{, , , } @c @DefescListEnd {\@}, , , } @deffn Escape @t{\@{} @deffnx Escape @t{\@}} @esindex \@{ @esindex \@} @cindex begin of conditional block (@code{\@{}) @cindex end of conditional block (@code{\@}}) @cindex conditional block, begin (@code{\@{}) @cindex conditional block, end (@code{\@}}) @cindex block, conditional, begin (@code{\@{}) @cindex block, condititional, end (@code{\@}}) In many cases, an if (or if-else) construct needs to execute more than one request. This can be done using the @code{\@{} and @code{\@}} escapes. The following example shows the possible ways to use these escapes (note the position of the opening and closing braces). @Example .ie t \@{\ . ds lq `` . ds rq '' .\@} .el \ .\@{\ . ds lq " . ds rq "\@} @endExample @c @endDefesc @end deffn @xref{Expressions}. @c --------------------------------------------------------------------- @node while, , if-else, Conditionals and Loops @subsection while @cindex while @code{gtroff} provides a looping construct using the @code{while} request, which is used much like the @code{if} (and related) requests. @Defreq {while, expr anything} Evaluate the expression @var{expr}, and repeatedly execute @var{anything} (the remainder of the line) until @var{expr} evaluates to@tie{}0. @Example .nr a 0 1 .while (\na < 9) \@{\ \n+a, .\@} \n+a @result{} 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 @endExample Some remarks. @cindex @code{de} request, and @code{while} @itemize @bullet @item The body of a @code{while} request is treated like the body of a @code{de} request: @code{gtroff} temporarily stores it in a macro which is deleted after the loop has been exited. It can considerably slow down a macro if the body of the @code{while} request (within the macro) is large. Each time the macro is executed, the @code{while} body is parsed and stored again as a temporary macro. @Example .de xxx . nr num 10 . while (\\n[num] > 0) \@{\ . \" many lines of code . nr num -1 . \@} .. @endExample @cindex recursive macros @cindex macros, recursive @noindent The traditional and ofter better solution (@acronym{UNIX} @code{troff} doesn't have the @code{while} request) is to use a recursive macro instead which is parsed only once during its definition. @Example .de yyy . if (\\n[num] > 0) \@{\ . \" many lines of code . nr num -1 . yyy . \@} .. . .de xxx . nr num 10 . yyy .. @endExample @noindent Note that the number of available recursion levels is set to@tie{}1000 (this is a compile-time constant value of @code{gtroff}). @item The closing brace of a @code{while} body must end a line. @Example .if 1 \@{\ . nr a 0 1 . while (\n[a] < 10) \@{\ . nop \n+[a] .\@}\@} @result{} unbalanced \@{ \@} @endExample @end itemize @endDefreq @Defreq {break, } @cindex @code{while} request, confusing with @code{br} @cindex @code{break} request, in a @code{while} loop @cindex @code{continue} request, in a @code{while} loop Break out of a @code{while} loop. Be sure not to confuse this with the @code{br} request (causing a line break). @endDefreq @Defreq {continue, } Finish the current iteration of a @code{while} loop, immediately restarting the next iteration. @endDefreq @xref{Expressions}. @c ===================================================================== @node Writing Macros, Page Motions, Conditionals and Loops, gtroff Reference @section Writing Macros @cindex writing macros @cindex macros, writing A @dfn{macro} is a collection of text and embedded commands which can be invoked multiple times. Use macros to define common operations. @DefreqList {de, name [@Var{end}]} @DefreqItem {de1, name [@Var{end}]} @DefreqItem {dei, name [@Var{end}]} @DefreqListEnd {dei1, name [@Var{end}]} Define a new macro named @var{name}. @code{gtroff} copies subsequent lines (starting with the next one) into an internal buffer until it encounters the line @samp{..} (two dots). The optional second argument to @code{de} changes this to a macro to @samp{.@var{end}}. There can be whitespace after the first dot in the line containing the ending token (either @samp{.} or macro @samp{@var{end}}). Here a small example macro called @samp{P} which causes a break and inserts some vertical space. It could be used to separate paragraphs. @Example .de P . br . sp .8v .. @endExample The following example defines a macro within another. Remember that expansion must be protected twice; once for reading the macro and once for executing. @Example \# a dummy macro to avoid a warning .de end .. . .de foo . de bar end . nop \f[B]Hallo \\\\$1!\f[] . end .. . .foo .bar Joe @result{} @b{Hallo Joe!} @endExample @noindent Since @code{\f} has no expansion, it isn't necessary to protect its backslash. Had we defined another macro within @code{bar} which takes a parameter, eight backslashes would be necessary before @samp{$1}. The @code{de1} request turns off compatibility mode while executing the macro. On entry, the current compatibility mode is saved and restored at exit. @Example .nr xxx 12345 . .de aa The value of xxx is \\n[xxx]. .. .de1 bb The value of xxx ix \\n[xxx]. .. . .cp 1 . .aa @result{} warning: number register ' not defined @result{} The value of xxx is 0xxx]. .bb @result{} The value of xxx ix 12345. @endExample The @code{dei} request defines a macro indirectly. That is, it expands strings whose names are @var{name} or @var{end} before performing the append. This: @Example .ds xx aa .ds yy bb .dei xx yy @endExample @noindent is equivalent to: @Example .de aa bb @endExample The @code{dei1} request is similar to @code{dei} but with compatibility mode switched off during execution of the defined macro. @pindex trace.tmac Using @file{trace.tmac}, you can trace calls to @code{de} and @code{de1}. Note that macro identifiers are shared with identifiers for strings and diversions. @endDefreq @DefreqList {am, name [@Var{end}]} @DefreqItem {am1, name [@Var{end}]} @DefreqItem {ami, name [@Var{end}]} @DefreqListEnd {ami1, name [@Var{end}]} @cindex appending to a macro (@code{am}) @cindex macro, appending (@code{am}) Works similarly to @code{de} except it appends onto the macro named @var{name}. So, to make the previously defined @samp{P} macro actually do indented instead of block paragraphs, add the necessary code to the existing macro like this: @Example .am P .ti +5n .. @endExample The @code{am1} request turns off compatibility mode while executing the appended macro piece. To be more precise, a @dfn{compatibility save} input token is inserted at the beginning of the appended code, and a @dfn{compatibility restore} input token at the end. The @code{ami} request appends indirectly, meaning that @code{gtroff} expands strings whose names are @var{name} or @var{end} before performing the append. The @code{ami1} request is similar to @code{ami} but compatibility mode is switched off during execution of the defined macro. @pindex trace.tmac Using @file{trace.tmac}, you can trace calls to @code{am} and @code{am1}. @endDefreq @xref{Strings}, for the @code{als} request to rename a macro. The @code{de}, @code{am}, @code{di}, @code{da}, @code{ds}, and @code{as} requests (together with its variants) only create a new object if the name of the macro, diversion or string diversion is currently undefined or if it is defined to be a request; normally they modify the value of an existing object. @Defreq {return, [@Var{anything}]} Exit a macro, immediately returning to the caller. If called with an argument, exit twice, namely the current macro and the macro one level higher. This is used to define a wrapper macro for @code{return} in @file{trace.tmac}. @endDefreq @menu * Copy-in Mode:: * Parameters:: @end menu @c --------------------------------------------------------------------- @node Copy-in Mode, Parameters, Writing Macros, Writing Macros @subsection Copy-in Mode @cindex copy-in mode @cindex mode, copy-in @cindex @code{\n}, when reading text for a macro @cindex @code{\$}, when reading text for a macro @cindex @code{\*}, when reading text for a macro @cindex @code{\\}, when reading text for a macro @cindex \@key{RET}, when reading text for a macro When @code{gtroff} reads in the text for a macro, string, or diversion, it copies the text (including request lines, but excluding escapes) into an internal buffer. Escapes are converted into an internal form, except for @code{\n}, @code{\$}, @code{\*}, @code{\\} and @code{\@key{RET}} which are evaluated and inserted into the text where the escape was located. This is known as @dfn{copy-in} mode or @dfn{copy} mode. What this means is that you can specify when these escapes are to be evaluated (either at copy-in time or at the time of use) by insulating the escapes with an extra backslash. Compare this to the @code{\def} and @code{\edef} commands in @TeX{}. The following example prints the numbers 20 and@tie{}10: @Example .nr x 20 .de y .nr x 10 \&\nx \&\\nx .. .y @endExample @c --------------------------------------------------------------------- @node Parameters, , Copy-in Mode, Writing Macros @subsection Parameters @cindex parameters The arguments to a macro or string can be examined using a variety of escapes. @Defreg {.$} @cindex number of arguments register (@code{.$}) The number of arguments passed to a macro or string. This is a read-only number register. Note that the @code{shift} request can change its value. @endDefreg Any individual argument can be retrieved with one of the following escapes: @DefescList {\\$, , n, } @DefescItem {\\$, @lparen{}, nn, } @DefescListEnd {\\$, @lbrack{}, nnn, @rbrack{}} @cindex copy-in mode, and macro arguments @cindex macro, arguments (@code{\$}) @cindex arguments, macro (@code{\$}) Retrieve the @var{n}@dmn{th}, @var{nn}@dmn{th} or @var{nnn}@dmn{th} argument. As usual, the first form only accepts a single number (larger than zero), the second a two-digit number (larger or equal to@tie{}10), and the third any positive integer value (larger than zero). Macros and strings can have an unlimited number of arguments. Note that due to copy-in mode, use two backslashes on these in actual use to prevent interpolation until the macro is actually invoked. @endDefesc @Defreq {shift, [@Var{n}]} Shift the arguments 1@tie{}position, or as many positions as specified by its argument. After executing this request, argument@tie{}@var{i} becomes argument @math{@var{i}-@var{n}}; arguments 1 to@tie{}@var{n} are no longer available. Shifting by negative amounts is currently undefined. The register @code{.$} is adjusted accordingly. @endDefreq @DefescList {\\$*, , , } @DefescListEnd {\\$@@, , , } In some cases it is convenient to use all of the arguments at once (for example, to pass the arguments along to another macro). The @code{\$*} escape concatenates all the arguments separated by spaces. A similar escape is @code{\$@@}, which concatenates all the arguments with each surrounded by double quotes, and separated by spaces. If not in compatibility mode, the input level of double quotes is preserved (see @ref{Request and Macro Arguments}). @endDefesc @Defesc {\\$0, , , } @cindex macro name register (@code{\$0}) @cindex @code{als} request, and @code{\$0} The name used to invoke the current macro. The @code{als} request can make a macro have more than one name. @Example .de generic-macro . ... . if \\n[error] \@{\ . tm \\$0: Houston, we have a problem. . return . \@} .. . .als foo generic-macro .als bar generic-macro @endExample @endDefesc @xref{Request and Macro Arguments}. @c ===================================================================== @node Page Motions, Drawing Requests, Writing Macros, gtroff Reference @section Page Motions @cindex page motions @cindex motions, page @xref{Manipulating Spacing}, for a discussion of the main request for vertical motion, @code{sp}. @DefreqList {mk, [@Var{reg}]} @DefreqListEnd {rt, [@Var{dist}]} @cindex marking vertical page location (@code{mk}) @cindex page location, vertical, marking (@code{mk}) @cindex location, vertical, page, marking (@code{mk}) @cindex vertical page location, marking (@code{mk}) @cindex returning to marked vertical page location (@code{rt}) @cindex page location, vertical, returning to marked (@code{rt}) @cindex location, vertical, page, returning to marked (@code{rt}) @cindex vertical page location, returning to marked (@code{rt}) The request @code{mk} can be used to mark a location on a page, for movement to later. This request takes a register name as an argument in which to store the current page location. With no argument it stores the location in an internal register. The results of this can be used later by the @code{rt} or the @code{sp} request (or the @code{\v} escape). The @code{rt} request returns @emph{upwards} to the location marked with the last @code{mk} request. If used with an argument, return to a position which distance from the top of the page is @var{dist} (no previous call to @code{mk} is necessary in this case). Default scaling indicator is @samp{v}. Here a primitive solution for a two-column macro. @Example .nr column-length 1.5i .nr column-gap 4m .nr bottom-margin 1m . @endExample @Example .de 2c . br . mk . ll \\n[column-length]u . wh -\\n[bottom-margin]u 2c-trap . nr right-side 0 .. . @endExample @Example .de 2c-trap . ie \\n[right-side] \@{\ . nr right-side 0 . po -(\\n[column-length]u + \\n[column-gap]u) . \" remove trap . wh -\\n[bottom-margin]u . \@} . el \@{\ . \" switch to right side . nr right-side 1 . po +(\\n[column-length]u + \\n[column-gap]u) . rt . \@} .. . @endExample @Example .pl 1.5i .ll 4i This is a small test which shows how the rt request works in combination with mk. .2c Starting here, text is typeset in two columns. Note that this implementation isn't robust and thus not suited for a real two-column macro. @endExample Result: @Example This is a small test which shows how the rt request works in combination with mk. Starting here, isn't robust text is typeset and thus not in two columns. suited for a Note that this real two-column implementation macro. @endExample @endDefreq The following escapes give fine control of movements about the page. @Defesc {\\v, ', e, '} @cindex vertical motion (@code{\v}) @cindex motion, vertical (@code{\v}) Move vertically, usually from the current location on the page (if no absolute position operator @samp{|} is used). The argument@tie{}@var{e} specifies the distance to move; positive is downwards and negative upwards. The default scaling indicator for this escape is @samp{v}. Beware, however, that @code{gtroff} continues text processing at the point where the motion ends, so you should always balance motions to avoid interference with text processing. @code{\v} doesn't trigger a trap. This can be quite useful; for example, consider a page bottom trap macro which prints a marker in the margin to indicate continuation of a footnote or something similar. @endDefesc There are some special-case escapes for vertical motion. @Defesc {\\r, , , } Move upwards@tie{}1@dmn{v}. @endDefesc @Defesc {\\u, , , } Move upwards@tie{}.5@dmn{v}. @endDefesc @Defesc {\\d, , , } Move down@tie{}.5@dmn{v}. @endDefesc @Defesc {\\h, ', e, '} @cindex inserting horizontal space (@code{\h}) @cindex horizontal space (@code{\h}) @cindex space, horizontal (@code{\h}) @cindex horizontal motion (@code{\h}) @cindex motion, horizontal (@code{\h}) Move horizontally, usually from the current location (if no absolute position operator @samp{|} is used). The expression@tie{}@var{e} indicates how far to move: positive is rightwards and negative leftwards. The default scaling indicator for this escape is @samp{m}. This horizontal space is not discarded at the end of a line. To insert discardable space of a certain length use the @code{ss} request. @endDefesc There are a number of special-case escapes for horizontal motion. @Defesc {\\@key{SP}, , , } @cindex space, unbreakable @cindex unbreakable space An unbreakable and unpaddable (i.e.@: not expanded during filling) space. (Note: This is a backslash followed by a space.) @endDefesc @Defesc {\\~, , , } An unbreakable space that stretches like a normal inter-word space when a line is adjusted. @endDefesc @Defesc {\\|, , , } A 1/6@dmn{th} em space. Ignored for TTY output devices (rounded to zero). @endDefesc @Defesc {\\^, , , } A 1/12@dmn{th} em space. Ignored for TTY output devices (rounded to zero). @endDefesc @Defesc {\\0, , , } @cindex space, width of a digit (@code{\0}) @cindex digit width space (@code{\0}) A space the size of a digit. @endDefesc The following string sets the @TeX{} logo: @Example .ds TeX T\h'-.1667m'\v'.224m'E\v'-.224m'\h'-.125m'X @endExample @DefescList {\\w, ', text, '} @DefregItem {st} @DefregItem {sb} @DefregItem {rst} @DefregItem {rsb} @DefregItem {ct} @DefregItem {ssc} @DefregListEnd {skw} @cindex width escape (@code{\w}) Return the width of the specified @var{text} in basic units. This allows horizontal movement based on the width of some arbitrary text (e.g.@: given as an argument to a macro). @Example The length of the string `abc' is \w'abc'u. @result{} The length of the string `abc' is 72u. @endExample Font changes may occur in @var{text} which don't affect current settings. After use, @code{\w} sets several registers: @table @code @item st @itemx sb The highest and lowest point of the baseline, respectively, in @var{text}. @item rst @itemx rsb Like the @code{st} and @code{sb} registers, but takes account of the heights and depths of glyphs. With other words, this gives the highest and lowest point of @var{text}. Values below the baseline are negative. @item ct Defines the kinds of glyphs occurring in @var{text}: @table @asis @item 0 only short glyphs, no descenders or tall glyphs. @item 1 at least one descender. @item 2 at least one tall glyph. @item 3 at least one each of a descender and a tall glyph. @end table @item ssc The amount of horizontal space (possibly negative) that should be added to the last glyph before a subscript. @item skw How far to right of the center of the last glyph in the @code{\w} argument, the center of an accent from a roman font should be placed over that glyph. @end table @endDefesc @DefescList {\\k, , p, } @DefescItem {\\k, @lparen{}, ps, } @DefescListEnd {\\k, @lbrack{}, position, @rbrack} @cindex saving horizontal input line position (@code{\k}) @cindex horizontal input line position, saving (@code{\k}) @cindex input line position, horizontal, saving (@code{\k}) @cindex position, horizontal input line, saving (@code{\k}) @cindex line, input, horizontal position, saving (@code{\k}) Store the current horizontal position in the @emph{input} line in number register with name @var{position} (one-character name@tie{}@var{p}, two-character name @var{ps}). Use this, for example, to return to the beginning of a string for highlighting or other decoration. @endDefesc @Defreg {hp} @cindex horizontal input line position register (@code{hp}) @cindex input line, horizontal position, register (@code{hp}) @cindex position, horizontal, in input line, register (@code{hp}) @cindex line, input, horizontal position, register (@code{hp}) The current horizontal position at the input line. @endDefreg @Defreg {.k} @cindex horizontal output line position register (@code{.k}) @cindex output line, horizontal position, register (@code{.k}) @cindex position, horizontal, in output line, register (@code{.k}) @cindex line, output, horizontal position, register (@code{.k}) A read-only number register containing the current horizontal output position (relative to the current indentation). @endDefreg @Defesc {\\o, ', abc, '} @cindex overstriking glyphs (@code{\o}) @cindex glyphs, overstriking (@code{\o}) Overstrike glyphs @var{a}, @var{b}, @var{c}, @dots{}; the glyphs are centered, and the resulting spacing is the largest width of the affected glyphs. @endDefesc @Defesc {\\z, , g, , } @cindex zero-width printing (@code{\z}, @code{\Z}) @cindex printing, zero-width (@code{\z}, @code{\Z}) Print glyph @var{g} with zero width, i.e., without spacing. Use this to overstrike glyphs left-aligned. @endDefesc @Defesc {\\Z, ', anything, '} @cindex zero-width printing (@code{\z}, @code{\Z}) @cindex printing, zero-width (@code{\z}, @code{\Z}) Print @var{anything}, then restore the horizontal and vertical position. The argument may not contain tabs or leaders. The following is an example of a strike-through macro: @Example .de ST .nr ww \w'\\$1' \Z@@\v'-.25m'\l'\\n[ww]u'@@\\$1 .. . This is .ST "a test" an actual emergency! @endExample @endDefesc @c ===================================================================== @node Drawing Requests, Traps, Page Motions, gtroff Reference @section Drawing Requests @cindex drawing requests @cindex requests for drawing @code{gtroff} provides a number of ways to draw lines and other figures on the page. Used in combination with the page motion commands (see @ref{Page Motions}, for more info), a wide variety of figures can be drawn. However, for complex drawings these operations can be quite cumbersome, and it may be wise to use graphic preprocessors like @code{gpic} or @code{ggrn}. @xref{gpic}, and @ref{ggrn}, for more information. All drawing is done via escapes. @DefescList {\\l, ', l, '} @DefescListEnd {\\l, ', lg, '} @cindex drawing horizontal lines (@code{\l}) @cindex horizontal line, drawing (@code{\l}) @cindex line, horizontal, drawing (@code{\l}) Draw a line horizontally. @var{l} is the length of the line to be drawn. If it is positive, start the line at the current location and draw to the right; its end point is the new current location. Negative values are handled differently: The line starts at the current location and draws to the left, but the current location doesn't move. @var{l} can also be specified absolutely (i.e.@: with a leading @samp{|}) which draws back to the beginning of the input line. Default scaling indicator is @samp{m}. @cindex underscore glyph (@code{\[ru]}) @cindex glyph, underscore (@code{\[ru]}) @cindex line drawing glyph @cindex glyph, for line drawing The optional second parameter@tie{}@var{g} is a glyph to draw the line with. If this second argument is not specified, @code{gtroff} uses the underscore glyph, @code{\[ru]}. @cindex zero width space character (@code{\&}) @cindex character, zero width space (@code{\&}) @cindex space character, zero width (@code{\&}) To separate the two arguments (to prevent @code{gtroff} from interpreting a drawing glyph as a scaling indicator if the glyph is represented by a single character) use @code{\&}. Here a small useful example: @Example .de box \[br]\\$*\[br]\l'|0\[rn]'\l'|0\[ul]' .. @endExample @noindent Note that this works by outputting a box rule (a vertical line), then the text given as an argument and then another box rule. Finally, the line drawing escapes both draw from the current location to the beginning of the @emph{input} line -- this works because the line length is negative, not moving the current point. @endDefesc @DefescList {\\L, ', l, '} @DefescListEnd {\\L, ', lg, '} @cindex drawing vertical lines (@code{\L}) @cindex vertical line drawing (@code{\L}) @cindex line, vertical, drawing (@code{\L}) @cindex line drawing glyph @cindex glyph for line drawing @cindex box rule glyph (@code{\[br]}) @cindex glyph, box rule (@code{\[br]}) Draw vertical lines. Its parameters are similar to the @code{\l} escape, except that the default scaling indicator is @samp{v}. The movement is downwards for positive values, and upwards for negative values. The default glyph is the box rule glyph, @code{\[br]}. As with the vertical motion escapes, text processing blindly continues where the line ends. @Example This is a \L'3v'test. @endExample @noindent Here the result, produced with @code{grotty}. @Example This is a | | |test. @endExample @endDefesc @Defesc {\\D, ', command arg @dots{}, '} The @code{\D} escape provides a variety of drawing functions. Note that on character devices, only vertical and horizontal lines are supported within @code{grotty}; other devices may only support a subset of the available drawing functions. The default scaling indicator for all subcommands of @code{\D} is @samp{m} for horizontal distances and @samp{v} for vertical ones. Exceptions are @w{@code{\D'f @dots{}'}} and @w{@code{\D't @dots{}'}} which use @code{u} as the default, and @w{@code{\D'F@var{x} @dots{}'}} which arguments are treated similar to the @code{defcolor} request. @table @code @item \D'l @var{dx} @var{dy}' @cindex line, drawing (@w{@code{\D'l @dots{}'}}) @cindex drawing a line (@w{@code{\D'l @dots{}'}}) Draw a line from the current location to the relative point specified by (@var{dx},@var{dy}), where positive values mean down and right, respectively. The end point of the line is the new current location. The following example is a macro for creating a box around a text string; for simplicity, the box margin is taken as a fixed value, 0.2@dmn{m}. @Example .de BOX . nr @@wd \w'\\$1' \h'.2m'\ \h'-.2m'\v'(.2m - \\n[rsb]u)'\ \D'l 0 -(\\n[rst]u - \\n[rsb]u + .4m)'\ \D'l (\\n[@@wd]u + .4m) 0'\ \D'l 0 (\\n[rst]u - \\n[rsb]u + .4m)'\ \D'l -(\\n[@@wd]u + .4m) 0'\ \h'.2m'\v'-(.2m - \\n[rsb]u)'\ \\$1\ \h'.2m' .. @endExample @noindent First, the width of the string is stored in register @code{@@wd}. Then, four lines are drawn to form a box, properly offset by the box margin. The registers @code{rst} and @code{rsb} are set by the @code{\w} escape, containing the largest height and depth of the whole string. @item \D'c @var{d}' @cindex circle, drawing (@w{@code{\D'c @dots{}'}}) @cindex drawing a circle (@w{@code{\D'c @dots{}'}}) Draw a circle with a diameter of@tie{}@var{d} with the leftmost point at the current position. After drawing, the current location is positioned at the rightmost point of the circle. @item \D'C @var{d}' @cindex circle, solid, drawing (@w{@code{\D'C @dots{}'}}) @cindex drawing a solid circle (@w{@code{\D'C @dots{}'}}) @cindex solid circle, drawing (@w{@code{\D'C @dots{}'}}) Draw a solid circle with the same parameters and behaviour as an outlined circle. No outline is drawn. @item \D'e @var{x} @var{y}' @cindex drawing an ellipse (@w{@code{\D'e @dots{}'}}) @cindex ellipse, drawing (@w{@code{\D'e @dots{}'}}) Draw an ellipse with a horizontal diameter of @var{x} and a vertical diameter of @var{y} with the leftmost point at the current position. After drawing, the current location is positioned at the rightmost point of the ellipse. @item \D'E @var{x} @var{y}' @cindex ellipse, solid, drawing (@w{@code{\D'E @dots{}'}}) @cindex drawing a solid ellipse (@w{@code{\D'E @dots{}'}}) @cindex solid ellipse, drawing (@w{@code{\D'E @dots{}'}}) Draw a solid ellipse with the same parameters and behaviour as an outlined ellipse. No outline is drawn. @item \D'a @var{dx1} @var{dy1} @var{dx2} @var{dy2}' @cindex arc, drawing (@w{@code{\D'a @dots{}'}}) @cindex drawing an arc (@w{@code{\D'a @dots{}'}}) Draw an arc clockwise from the current location through the two specified relative locations (@var{dx1},@var{dy1}) and (@var{dx2},@var{dy2}). The coordinates of the first point are relative to the current position, and the coordinates of the second point are relative to the first point. After drawing, the current position is moved to the final point of the arc. @item \D'~ @var{dx1} @var{dy1} @var{dx2} @var{dy2} @dots{}' @cindex drawing a spline (@w{@code{\D'~ @dots{}'}}) @cindex spline, drawing (@w{@code{\D'~ @dots{}'}}) Draw a spline from the current location to the relative point (@var{dx1},@var{dy1}) and then to (@var{dx2},@var{dy2}), and so on. The current position is moved to the terminal point of the drawn curve. @item \D'f @var{n}' @cindex gray shading (@w{@code{\D'f @dots{}'}}) @cindex shading filled objects (@w{@code{\D'f @dots{}'}}) Set the shade of gray to be used for filling solid objects to@tie{}@var{n}; @var{n}@tie{}must be an integer between 0 and@tie{}1000, where 0 corresponds solid white and 1000 to solid black, and values in between correspond to intermediate shades of gray. This applies only to solid circles, solid ellipses, and solid polygons. By default, a level of 1000 is used. Despite of being silly, the current point is moved horizontally to the right by@tie{}@var{n}. @cindex @w{@code{\D'f @dots{}'}} and horizontal resolution Don't use this command! It has the serious drawback that it will be always rounded to the next integer multiple of the horizontal resolution (the value of the @code{hor} keyword in the @file{DESC} file). Use @code{\M} (@pxref{Colors}) or @w{@code{\D'Fg @dots{}'}} instead. @item \D'p @var{dx1} @var{dy1} @var{dx2} @var{dy2} @dots{}' @cindex drawing a polygon (@w{@code{\D'p @dots{}'}}) @cindex polygon, drawing (@w{@code{\D'p @dots{}'}}) Draw a polygon from the current location to the relative position (@var{dx1},@var{dy1}) and then to (@var{dx2},@var{dy2}) and so on. When the specified data points are exhausted, a line is drawn back to the starting point. The current position is changed by adding the sum of all arguments with odd index to the actual horizontal position and the even ones to the vertical position. @item \D'P @var{dx1} @var{dy1} @var{dx2} @var{dy2} @dots{}' @cindex polygon, solid, drawing (@w{@code{\D'P @dots{}'}}) @cindex drawing a solid polygon (@w{@code{\D'P @dots{}'}}) @cindex solid polygon, drawing (@w{@code{\D'P @dots{}'}}) Draw a solid polygon with the same parameters and behaviour as an outlined polygon. No outline is drawn. Here a better variant of the box macro to fill the box with some color. Note that the box must be drawn before the text since colors in @code{gtroff} are not transparent; the filled polygon would hide the text completely. @Example .de BOX . nr @@wd \w'\\$1' \h'.2m'\ \h'-.2m'\v'(.2m - \\n[rsb]u)'\ \M[lightcyan]\ \D'P 0 -(\\n[rst]u - \\n[rsb]u + .4m) \ (\\n[@@wd]u + .4m) 0 \ 0 (\\n[rst]u - \\n[rsb]u + .4m) \ -(\\n[@@wd]u + .4m) 0'\ \h'.2m'\v'-(.2m - \\n[rsb]u)'\ \M[]\ \\$1\ \h'.2m' .. @endExample @item \D't @var{n}' @cindex line thickness (@w{@code{\D't @dots{}'}}) @cindex thickness of lines (@w{@code{\D't @dots{}'}}) Set the current line thickness to @var{n}@tie{}machine units. A value of zero selects the smallest available line thickness. A negative value makes the line thickness proportional to the current point size (this is the default behaviour of @acronym{AT&T} @code{troff}). Despite of being silly, the current point is moved horizontally to the right by@tie{}@var{n}. @item \D'F@var{scheme} @var{color_components}' @cindex unnamed fill colors (@code{\D'F@dots{}'}) @cindex fill colors, unnamed (@code{\D'F@dots{}'}) @cindex colors, fill, unnamed (@code{\D'F@dots{}'}) Change current fill color. @var{scheme} is a single letter denoting the color scheme: @samp{r} (rgb), @samp{c} (cmy), @samp{k} (cmyk), @samp{g} (gray), or @samp{d} (default color). The color components use exactly the same syntax as in the @code{defcolor} request (@pxref{Colors}); the command @code{\D'Fd'} doesn't take an argument. @emph{No} position changing! Examples: @Example @endExample \D'Fg .3' \" same gray as \D'f 700' \D'Fr #0000ff' \" blue @end table @endDefesc @xref{Graphics Commands}. @Defesc {\\b, ', string, '} @cindex pile, glyph (@code{\b}) @cindex glyph pile (@code{\b}) @cindex stacking glyphs (@code{\b}) @dfn{Pile} a sequence of glyphs vertically, and center it vertically on the current line. Use it to build large brackets and braces. Here an example how to create a large opening brace: @Example \b'\[lt]\[bv]\[lk]\[bv]\[lb]' @endExample @cindex @code{\b}, limitations @cindex limitations of @code{\b} escape The first glyph is on the top, the last glyph in @var{string} is at the bottom. Note that @code{gtroff} separates the glyphs vertically by 1@dmn{m}, and the whole object is centered 0.5@dmn{m} above the current baseline; the largest glyph width is used as the width for the whole object. This rather unflexible positioning algorithm doesn't work with @option{-Tdvi} since the bracket pieces vary in height for this device. Instead, use the @code{eqn} preprocessor. @xref{Manipulating Spacing}, how to adjust the vertical spacing with the @code{\x} escape. @endDefesc @c ===================================================================== @node Traps, Diversions, Drawing Requests, gtroff Reference @section Traps @cindex traps @dfn{Traps} are locations, which, when reached, call a specified macro. These traps can occur at a given location on the page, at a given location in the current diversion, at a blank line, after a certain number of input lines, or at the end of input. @cindex planting a trap @cindex trap, planting Setting a trap is also called @dfn{planting}. @cindex trap, springing @cindex springing a trap It is also said that a trap is @dfn{sprung} if the associated macro is executed. @menu * Page Location Traps:: * Diversion Traps:: * Input Line Traps:: * Blank Line Traps:: * End-of-input Traps:: @end menu @c --------------------------------------------------------------------- @node Page Location Traps, Diversion Traps, Traps, Traps @subsection Page Location Traps @cindex page location traps @cindex traps, page location @dfn{Page location traps} perform an action when @code{gtroff} reaches or passes a certain vertical location on the page. Page location traps have a variety of purposes, including: @itemize @item setting headers and footers @item setting body text in multiple columns @item setting footnotes @end itemize @DefreqList {vpt, flag} @DefregListEnd {.vpt} @cindex enabling vertical position traps (@code{vpt}) @cindex vertical position traps, enabling (@code{vpt}) @cindex vertical position trap enable register (@code{.vpt}) Enable vertical position traps if @var{flag} is non-zero, or disables them otherwise. Vertical position traps are traps set by the @code{wh} or @code{dt} requests. Traps set by the @code{it} request are not vertical position traps. The parameter that controls whether vertical position traps are enabled is global. Initially vertical position traps are enabled. The current setting of this is available in the @code{.vpt} read-only number register. Note that a page can't be ejected if @code{vpt} is set to zero. @endDefreq @Defreq {wh, dist [@Var{macro}]} Set a page location trap. Non-negative values for @var{dist} set the trap relative to the top of the page; negative values set the trap relative to the bottom of the page. Default scaling indicator is @samp{v}. @var{macro} is the name of the macro to execute when the trap is sprung. If @var{macro} is missing, remove the first trap (if any) at @var{dist}. @cindex page headers @cindex page footers @cindex headers @cindex footers The following is a simple example of how many macro packages set headers and footers. @Example .de hd \" Page header ' sp .5i . tl 'Title''date' ' sp .3i .. . .de fo \" Page footer ' sp 1v . tl ''%'' ' bp .. . .wh 0 hd \" trap at top of the page .wh -1i fo \" trap one inch from bottom @endExample A trap at or below the bottom of the page is ignored; it can be made active by either moving it up or increasing the page length so that the trap is on the page. It is possible to have more than one trap at the same location; to do so, the traps must be defined at different locations, then moved together with the @code{ch} request; otherwise the second trap would replace the first one. Earlier defined traps hide later defined traps if moved to the same position (the many empty lines caused by the @code{bp} request are omitted in the following example): @Example .de a . nop a .. .de b . nop b .. .de c . nop c .. . .wh 1i a .wh 2i b .wh 3i c .bp @result{} a b c @endExample @Example .ch b 1i .ch c 1i .bp @result{} a @endExample @Example .ch a 0.5i .bp @result{} a b @endExample @endDefreq @Defreg {.t} @cindex distance to next trap register (@code{.t}) @cindex trap, distance, register (@code{.t}) A read-only number register holding the distance to the next trap. If there are no traps between the current position and the bottom of the page, it contains the distance to the page bottom. In a diversion, the distance to the page bottom is infinite (the returned value is the biggest integer which can be represented in @code{groff}) if there are no diversion traps. @endDefreg @Defreq {ch, macro [@Var{dist}]} @cindex changing trap location (@code{ch}) @cindex trap, changing location (@code{ch}) Change the location of a trap. The first argument is the name of the macro to be invoked at the trap, and the second argument is the new location for the trap (note that the parameters are specified in opposite order as in the @code{wh} request). This is useful for building up footnotes in a diversion to allow more space at the bottom of the page for them. Default scaling indicator for @var{dist} is @samp{v}. If @var{dist} is missing, the trap is removed. @c XXX @ignore @Example ... (simplified) footnote example ... @endExample @end ignore @endDefreq @Defreg {.ne} The read-only number register @code{.ne} contains the amount of space that was needed in the last @code{ne} request that caused a trap to be sprung. Useful in conjunction with the @code{.trunc} register. @xref{Page Control}, for more information. Since the @code{.ne} register is only set by traps it doesn't make much sense to use it outside of trap macros. @endDefreg @Defreg {.trunc} @cindex @code{ne} request, and the @code{.trunc} register @cindex truncated vertical space register (@code{.trunc}) A read-only register containing the amount of vertical space truncated by the most recently sprung vertical position trap, or, if the trap was sprung by an @code{ne} request, minus the amount of vertical motion produced by the @code{ne} request. In other words, at the point a trap is sprung, it represents the difference of what the vertical position would have been but for the trap, and what the vertical position actually is. Since the @code{.trunc} register is only set by traps it doesn't make much sense to use it outside of trap macros. @endDefreg @Defreg {.pe} @cindex @code{bp} request, and traps (@code{.pe}) @cindex traps, sprung by @code{bp} request (@code{.pe}) @cindex page ejecting register (@code{.pe}) A read-only register which is set to@tie{}1 while a page is ejected with the @code{bp} request (or by the end of input). Outside of traps this register is always zero. In the following example, only the second call to@tie{}@code{x} is caused by @code{bp}. @Example .de x \&.pe=\\n[.pe] .br .. .wh 1v x .wh 4v x A line. .br Another line. .br @result{} A line. .pe=0 Another line. .pe=1 @endExample @endDefreg @cindex diversions, and traps @cindex traps, and diversions An important fact to consider while designing macros is that diversions and traps do not interact normally. For example, if a trap invokes a header macro (while outputting a diversion) which tries to change the font on the current page, the effect will not be visible before the diversion has completely been printed (except for input protected with @code{\!} or @code{\?}) since the data in the diversion is already formatted. In most cases, this is not the expected behaviour. @c --------------------------------------------------------------------- @node Diversion Traps, Input Line Traps, Page Location Traps, Traps @subsection Diversion Traps @cindex diversion traps @cindex traps, diversion @Defreq {dt, [@Var{dist} @Var{macro}]} @cindex @code{.t} register, and diversions @cindex setting diversion trap (@code{dt}) @cindex diversion trap, setting (@code{dt}) @cindex trap, diversion, setting (@code{dt}) Set a trap @emph{within} a diversion. @var{dist} is the location of the trap (identical to the @code{wh} request; default scaling indicator is @samp{v}) and @var{macro} is the name of the macro to be invoked. If called without arguments, the diversion trap is removed. Note that there exists only a single diversion trap. The number register @code{.t} still works within diversions. @xref{Diversions}, for more information. @endDefreq @c --------------------------------------------------------------------- @node Input Line Traps, Blank Line Traps, Diversion Traps, Traps @subsection Input Line Traps @cindex input line traps @cindex traps, input line @DefreqList {it, n macro} @DefreqItem {itc, n macro} @cindex setting input line trap (@code{it}) @cindex input line trap, setting (@code{it}) @cindex trap, input line, setting (@code{it}) Set an input line trap. @var{n}@tie{}is the number of lines of input which may be read before springing the trap, @var{macro} is the macro to be invoked. Request lines are not counted as input lines. For example, one possible use is to have a macro which prints the next @var{n}@tie{}lines in a bold font. @Example .de B . it \\$1 B-end . ft B .. . .de B-end . ft R .. @endExample @cindex input line traps and interrupted lines (@code{itc}) @cindex interrupted lines and input line traps (@code{itc}) @cindex traps, input line, and interrupted lines (@code{itc}) @cindex lines, interrupted, and input line traps (@code{itc}) The @code{itc} request is identical except that an interrupted text line (ending with @code{\c}) is not counted as a separate line. Both requests are associated with the current environment (@pxref{Environments}); switching to another environment disables the current input trap, and going back reactivates it, restoring the number of already processed lines. @endDefreq @c --------------------------------------------------------------------- @node Blank Line Traps, End-of-input Traps, Input Line Traps, Traps @subsection Blank Line Traps @cindex blank line traps @cindex traps, blank line @Defreq {blm, macro} @cindex blank line macro (@code{blm}) Set a blank line trap. @code{gtroff} executes @var{macro} when it encounters a blank line in the input file. @endDefreq @c --------------------------------------------------------------------- @node End-of-input Traps, , Blank Line Traps, Traps @subsection End-of-input Traps @cindex end-of-input traps @cindex traps, end-of-input @Defreq {em, macro} @cindex setting end-of-input trap (@code{em}) @cindex end-of-input trap, setting (@code{em}) @cindex trap, end-of-input, setting (@code{em}) @cindex end-of-input macro (@code{em}) @cindex macro, end-of-input (@code{em}) Set a trap at the end of input. @var{macro} is executed after the last line of the input file has been processed. For example, if the document had to have a section at the bottom of the last page for someone to approve it, the @code{em} request could be used. @Example .de approval . ne 5v . sp |(\\n[.t] - 6v) . in +4i . lc _ . br Approved:\t\a . sp Date:\t\t\a .. . .em approval @endExample @endDefreq @c ===================================================================== @node Diversions, Environments, Traps, gtroff Reference @section Diversions @cindex diversions In @code{gtroff} it is possible to @dfn{divert} text into a named storage area. Due to the similarity to defining macros it is sometimes said to be stored in a macro. This is used for saving text for output at a later time, which is useful for keeping blocks of text on the same page, footnotes, tables of contents, and indices. @cindex top-level diversion @cindex diversion, top-level For orthogonality it is said that @code{gtroff} is in the @dfn{top-level diversion} if no diversion is active (i.e., the data is diverted to the output device). @DefreqList {di, macro} @DefreqListEnd {da, macro} @cindex beginning diversion (@code{di}) @cindex diversion, beginning (@code{di}) @cindex ending diversion (@code{di}) @cindex diversion, ending (@code{di}) @cindex appending to a diversion (@code{da}) @cindex diversion, appending (@code{da}) Begin a diversion. Like the @code{de} request, it takes an argument of a macro name to divert subsequent text into. The @code{da} macro appends to an existing diversion. @code{di} or @code{da} without an argument ends the diversion. @endDefreq @DefreqList {box, macro} @DefreqListEnd {boxa, macro} Begin (or appends to) a diversion like the @code{di} and @code{da} requests. The difference is that @code{box} and @code{boxa} do not include a partially-filled line in the diversion. Compare this: @Example Before the box. .box xxx In the box. .br .box After the box. .br @result{} Before the box. After the box. .xxx @result{} In the box. @endExample @noindent with this: @Example Before the diversion. .di yyy In the diversion. .br .di After the diversion. .br @result{} After the diversion. .yyy @result{} Before the diversion. In the diversion. @endExample @code{box} or @code{boxa} without an argument ends the diversion. @endDefreq @DefregList {.z} @DefregListEnd {.d} @cindex @code{nl} register, and @code{.d} @cindex nested diversions @cindex diversion, nested @cindex diversion name register (@code{.z}) @cindex vertical position in diversion register (@code{.d}) @cindex position, vertical, in diversion, register (@code{.d}) @cindex diversion, vertical position in, register (@code{.d}) Diversions may be nested. The read-only number register @code{.z} contains the name of the current diversion (this is a string-valued register). The read-only number register @code{.d} contains the current vertical place in the diversion. If not in a diversion it is the same as register @code{nl}. @endDefreg @Defreg {.h} @cindex high-water mark register (@code{.h}) @cindex mark, high-water, register (@code{.h}) @cindex position of lowest text line (@code{.h}) @cindex text line, position of lowest (@code{.h}) The @dfn{high-water mark} on the current page. It corresponds to the text baseline of the lowest line on the page. This is a read-only register. @Example .tm .h==\n[.h], nl==\n[nl] @result{} .h==0, nl==-1 This is a test. .br .sp 2 .tm .h==\n[.h], nl==\n[nl] @result{} .h==40, nl==120 @endExample @cindex @code{.h} register, difference to @code{nl} @cindex @code{nl} register, difference to @code{.h} @noindent As can be seen in the previous example, empty lines are not considered in the return value of the @code{.h} register. @endDefreg @DefregList {dn} @DefregListEnd {dl} @cindex @code{dn} register, and @code{da} (@code{boxa}) @cindex @code{dl} register, and @code{da} (@code{boxa}) @cindex @code{da} request, and @code{dn} (@code{dl}) @cindex @code{boxa} request, and @code{dn} (@code{dl}) After completing a diversion, the read-write number registers @code{dn} and @code{dl} contain the vertical and horizontal size of the diversion. Note that only the just processed lines are counted: For the computation of @code{dn} and @code{dl}, the requests @code{da} and @code{boxa} are handled as if @code{di} and @code{box} had been used -- lines which have been already stored in a macro are not taken into account. @Example .\" Center text both horizontally & vertically . .\" Enclose macro definitions in .eo and .ec .\" to avoid the doubling of the backslash .eo .\" macro .(c starts centering mode .de (c . br . ev (c . evc 0 . in 0 . nf . di @@c .. @endExample @Example .\" macro .)c terminates centering mode .de )c . br . ev . di . nr @@s (((\n[.t]u - \n[dn]u) / 2u) - 1v) . sp \n[@@s]u . ce 1000 . @@c . ce 0 . sp \n[@@s]u . br . fi . rr @@s . rm @@s . rm @@c .. .\" End of macro definitions, restore escape mechanism .ec @endExample @endDefreg @DefescList {\\!, , , } @DefescListEnd {\\?, , anything, \\?} @cindex transparent output (@code{\!}, @code{\?}) @cindex output, transparent (@code{\!}, @code{\?}) Prevent requests, macros, and escapes from being interpreted when read into a diversion. Both escapes take the given text and @dfn{transparently} embed it into the diversion. This is useful for macros which shouldn't be invoked until the diverted text is actually output. The @code{\!} escape transparently embeds text up to and including the end of the line. The @code{\?} escape transparently embeds text until the next occurrence of the @code{\?} escape. Example: @Example \?@var{anything}\? @endExample @noindent @var{anything} may not contain newlines; use @code{\!} to embed newlines in a diversion. The escape sequence @code{\?} is also recognized in copy mode and turned into a single internal code; it is this code that terminates @var{anything}. Thus the following example prints@tie{}4. @Example .nr x 1 .nf .di d \?\\?\\\\?\\\\\\\\nx\\\\?\\?\? .di .nr x 2 .di e .d .di .nr x 3 .di f .e .di .nr x 4 .f @endExample Both escapes read the data in copy mode. @cindex @code{\!}, in top-level diversion @cindex top-level diversion, and @code{\!} @cindex diversion, top-level, and @code{\!} If @code{\!} is used in the top-level diversion, its argument is directly embedded into the @code{gtroff} intermediate output. This can be used for example to control a postprocessor which processes the data before it is sent to the device driver. @cindex @code{\?}, in top-level diversion @cindex top-level diversion, and @code{\?} @cindex diversion, top-level, and @code{\?} The @code{\?} escape used in the top-level diversion produces no output at all; its argument is simply ignored. @endDefesc @cindex @code{\!}, and @code{output} @cindex @code{output} request, and @code{\!} @Defreq {output, string} Emit @var{string} directly to the @code{gtroff} intermediate output (subject to copy-mode interpretation); this is similar to @code{\!} used at the top level. An initial double quote in @var{string} is stripped off to allow initial blanks. This request can't be used before the first page has started -- if you get an error, simply insert @code{.br} before the @code{output} request. Without argument, @code{output} is ignored. Use with caution! It is normally only needed for mark-up used by a postprocessor which does something with the output before sending it to the output device, filtering out @var{string} again. @endDefreq @Defreq {asciify, div} @cindex unformatting diversions (@code{asciify}) @cindex diversion, unformatting (@code{asciify}) @cindex @code{trin} request, and @code{asciify} @dfn{Unformat} the diversion specified by @var{div} in such a way that @acronym{ASCII} characters, characters translated with the @code{trin} request, space characters, and some escape sequences that were formatted and diverted are treated like ordinary input characters when the diversion is reread. It can be also used for gross hacks; for example, the following sets register@tie{}@code{n} to@tie{}1. @Example .tr @@. .di x @@nr n 1 .br .di .tr @@@@ .asciify x .x @endExample @xref{Copy-in Mode}. @endDefreq @Defreq {unformat, div} Like @code{asciify}, unformat the specified diversion. However, @code{unformat} only unformats spaces and tabs between words. Unformatted tabs are treated as input tokens, and spaces are stretchable again. The vertical size of lines is not preserved; glyph information (font, font size, space width, etc.)@: is retained. @endDefreq @c ===================================================================== @node Environments, Suppressing output, Diversions, gtroff Reference @section Environments @cindex environments It happens frequently that some text should be printed in a certain format regardless of what may be in effect at the time, for example, in a trap invoked macro to print headers and footers. To solve this @code{gtroff} processes text in @dfn{environments}. An environment contains most of the parameters that control text processing. It is possible to switch amongst these environments; by default @code{gtroff} processes text in environment@tie{}0. The following is the information kept in an environment. @itemize @bullet @item font parameters (size, family, style, glyph height and slant, space and sentence space size) @item page parameters (line length, title length, vertical spacing, line spacing, indentation, line numbering, centering, right-justifying, underlining, hyphenation data) @item fill and adjust mode @item tab stops, tab and leader characters, escape character, no-break and hyphen indicators, margin character data @item partially collected lines @item input traps @item drawing and fill colours @end itemize These environments may be given arbitrary names (see @ref{Identifiers}, for more info). Old versions of @code{troff} only had environments named @samp{0}, @samp{1}, and @samp{2}. @DefreqList {ev, [@Var{env}]} @DefregListEnd {.ev} @cindex switching environments (@code{ev}) @cindex environment, switching (@code{ev}) @cindex environment number/name register (@code{.ev}) Switch to another environment. The argument @var{env} is the name of the environment to switch to. With no argument, @code{gtroff} switches back to the previous environment. There is no limit on the number of named environments; they are created the first time that they are referenced. The @code{.ev} read-only register contains the name or number of the current environment. This is a string-valued register. Note that a call to @code{ev} (with argument) pushes the previously active environment onto a stack. If, say, environments @samp{foo}, @samp{bar}, and @samp{zap} are called (in that order), the first @code{ev} request without parameter switches back to environment @samp{bar} (which is popped off the stack), and a second call switches back to environment @samp{foo}. Here is an example: @Example .ev footnote-env .fam N .ps 6 .vs 8 .ll -.5i .ev ... .ev footnote-env \(dg Note the large, friendly letters. .ev @endExample @endDefreq @Defreq {evc, env} @cindex copying environment (@code{evc}) @cindex environment, copying (@code{evc}) Copy the environment @var{env} into the current environment. The following environment data is not copied: @itemize @bullet @item Partially filled lines. @item The status whether the previous line was interrupted. @item The number of lines still to center, or to right-justify, or to underline (with or without underlined spaces); they are set to zero. @item The status whether a temporary indent is active. @item Input traps and its associated data. @item Line numbering mode is disabled; it can be reactivated with @w{@samp{.nm +0}}. @item The number of consecutive hyphenated lines (set to zero). @end itemize @endDefreq @DefregList {.w} @DefregItem {.cht} @DefregItem {.cdp} @DefregListEnd {.csk} @cindex environment, dimensions of last glyph (@code{.w}, @code{.cht}, @code{.cdp}, @code{.csk}) @cindex width, of last glyph (@code{.w}) @cindex height, of last glyph (@code{.cht}) @cindex depth, of last glyph (@code{.cdp}) @cindex skew, of last glyph (@code{.csk}) @cindex last glyph, dimensions (@code{.w}, @code{.cht}, @code{.cdp}, @code{.csk}) @cindex glyph, last, dimensions (@code{.w}, @code{.cht}, @code{.cdp}, @code{.csk}) The @code{\n[.w]} register contains the width of the last glyph added to the current environment. The @code{\n[.cht]} register contains the height of the last glyph added to the current environment. The @code{\n[.cdp]} register contains the depth of the last glyph added to the current environment. It is positive for glyphs extending below the baseline. The @code{\n[.csk]} register contains the @dfn{skew} (how far to the right of the glyph's center that @code{gtroff} should place an accent) of the last glyph added to the current environment. @endDefreg @Defreg {.n} @cindex environment, previous line length (@code{.n}) @cindex line length, previous (@code{.n}) @cindex length of previous line (@code{.n}) @cindex previous line length (@code{.n}) The @code{\n[.n]} register contains the length of the previous output line in the current environment. @endDefreg @c ===================================================================== @node Suppressing output, Colors, Environments, gtroff Reference @section Suppressing output @Defesc {\\O, , num, } @cindex suppressing output (@code{\O}) @cindex output, suppressing (@code{\O}) Disable or enable output depending on the value of @var{num}: @table @samp @item \O0 Disable any glyphs from being emitted to the device driver, provided that the escape occurs at the outer level (see @code{\O[3]} and @code{\O[4]}). Motion is not suppressed so effectively @code{\O[0]} means @emph{pen up}. @item \O1 Enable output of glyphs, provided that the escape occurs at the outer level. @end table @vindex opminx @vindex opminy @vindex opmaxx @vindex opmaxy @code{\O0} and @code{\O1} also reset the four registers @samp{opminx}, @samp{opminy}, @samp{opmaxx}, and @samp{opmaxy} to @minus{}1. @xref{Register Index}. These four registers mark the top left and bottom right hand corners of a box which encompasses all written glyphs. For example the input text: @Example Hello \O[0]world \O[1]this is a test. @endExample @noindent produces the following output: @Example Hello this is a test. @endExample @table @samp @item \O2 Provided that the escape occurs at the outer level, enable output of glyphs and also write out to @code{stderr} the page number and four registers encompassing the glyphs previously written since the last call to @code{\O}. @item \O3 Begin a nesting level. At start-up, @code{gtroff} is at outer level. @item \O4 End a nesting level. @item \O[5@var{P}@var{filename}] This escape is @code{grohtml} specific. Provided that this escape occurs at the outer nesting level write the @code{filename} to @code{stderr}. The position of the image, @var{P}, must be specified and must be one of @code{l}, @code{r}, @code{c}, or@tie{}@code{i} (left, right, centered, inline). @var{filename} will be associated with the production of the next inline image. @end table @endDefesc @c ===================================================================== @node Colors, I/O, Suppressing output, gtroff Reference @section Colors @cindex colors @DefreqList {color, [@Var{n}]} @DefregListEnd {.color} If @var{n} is missing or non-zero, activate colors (this is the default); otherwise, turn it off. The read-only number register @code{.color} is@tie{}1 if colors are active, 0@tie{}otherwise. Internally, @code{color} sets a global flag; it does not produce a token. Similar to the @code{cp} request, you should use it at the beginning of your document to control color output. Colors can be also turned off with the @option{-c} command line option. @endDefreq @Defreq {defcolor, ident scheme color_components} Define color with name @var{ident}. @var{scheme} can be one of the following values: @code{rgb} (three components), @code{cmy} (three components), @code{cmyk} (four components), and @code{gray} or @code{grey} (one component). @cindex default color @cindex color, default Color components can be given either as a hexadecimal string or as positive decimal integers in the range 0--65535. A hexadecimal string contains all color components concatenated. It must start with either @code{#} or @code{##}; the former specifies hex values in the range 0--255 (which are internally multiplied by@tie{}257), the latter in the range 0--65535. Examples: @code{#FFC0CB} (pink), @code{##ffff0000ffff} (magenta). The default color name @c{default} can't be redefined; its value is device-specific (usually black). It is possible that the default color for @code{\m} and @code{\M} is not identical. @cindex @code{f} unit, and colors @cindex unit, @code{f}, and colors A new scaling indicator@tie{}@code{f} has been introduced which multiplies its value by 65536; this makes it convenient to specify color components as fractions in the range 0 to@tie{}1 (1f equals 65536u). Example: @Example .defcolor darkgreen rgb 0.1f 0.5f 0.2f @endExample Note that @code{f} is the default scaling indicator for the @code{defcolor} request, thus the above statement is equivalent to @Example .defcolor darkgreen rgb 0.1 0.5 0.2 @endExample @endDefreq @DefescList {\\m, , c, } @DefescItem {\\m, @lparen{}, co, } @DefescItem {\\m, @lbrack{}, color, @rbrack} @DefregListEnd {.m} Set drawing color. The following example shows how to turn the next four words red. @Example \m[red]these are in red\m[] and these words are in black. @endExample The escape @code{\m[]} returns to the previous color. @cindex drawing color name register (@code{.m}) @cindex name, drawing color, register (@code{.m}) @cindex color name, drawing, register (@code{.m}) The name of the current drawing color is available in the read-only, string-valued number register @samp{.m}. The drawing color is associated with the current environment (@pxref{Environments}). Note that @code{\m} doesn't produce an input token in @code{gtroff}. As a consequence, it can be used in requests like @code{mc} (which expects a single character as an argument) to change the color on the fly: @Example .mc \m[red]x\m[] @endExample @endDefesc @DefescList {\\M, , c, } @DefescItem {\\M, @lparen{}, co, } @DefescItem {\\M, @lbrack{}, color, @rbrack} @DefregListEnd {.M} Set background color for filled objects drawn with the @code{\D'@dots{}'} commands. A red ellipse can be created with the following code: @Example \M[red]\h'0.5i'\D'E 2i 1i'\M[] @endExample The escape @code{\M[]} returns to the previous fill color. @cindex background color name register (@code{.M}) @cindex name, background color, register (@code{.M}) @cindex color name, background, register (@code{.M}) The name of the current background color is available in the read-only, string-valued number register @samp{.M}. The fill color is associated with the current environment (@pxref{Environments}). Note that @code{\M} doesn't produce an input token in @code{gtroff}. @endDefesc @c ===================================================================== @node I/O, Postprocessor Access, Colors, gtroff Reference @section I/O @cindex i/o @cindex input and output requests @cindex requests for input and output @cindex output and input requests @code{gtroff} has several requests for including files: @Defreq {so, file} @cindex including a file (@code{so}) @cindex file, inclusion (@code{so}) Read in the specified @var{file} and includes it in place of the @code{so} request. This is quite useful for large documents, e.g.@: keeping each chapter in a separate file. @xref{gsoelim}, for more information. Since @code{gtroff} replaces the @code{so} request with the contents of @code{file}, it makes a difference whether the data is terminated with a newline or not: Assuming that file @file{xxx} contains the word @samp{foo} without a final newline, this @Example This is .so xxx bar @endExample @noindent yields @samp{This is foobar}. The search path for @var{file} can be controlled with the @option{-I} command line option. @endDefreq @Defreq {pso, command} Read the standard output from the specified @var{command} and includes it in place of the @code{pso} request. @cindex safer mode @cindex mode, safer @cindex unsafe mode @cindex mode, unsafe This request causes an error if used in safer mode (which is the default). Use @code{groff}'s or @code{troff}'s @option{-U} option to activate unsafe mode. The comment regarding a final newline for the @code{so} request is valid for @code{pso} also. @endDefreq @Defreq {mso, file} Identical to the @code{so} request except that @code{gtroff} searches for the specified @var{file} in the same directories as macro files for the the @option{-m} command line option. If the file name to be included has the form @file{@var{name}.tmac} and it isn't found, @code{mso} tries to include @file{tmac.@var{name}} and vice versa. @endDefreq @DefreqList {trf, file} @DefreqListEnd {cf, file} @cindex transparent output (@code{cf}, @code{trf}) @cindex output, transparent (@code{cf}, @code{trf}) Transparently output the contents of @var{file}. Each line is output as if it were preceded by @code{\!}; however, the lines are not subject to copy mode interpretation. If the file does not end with a newline, then a newline is added (@code{trf} only). For example, to define a macro@tie{}@code{x} containing the contents of file@tie{}@file{f}, use @Example .di x .trf f .di @endExample Both @code{trf} and @code{cf}, when used in a diversion, embeds an object in the diversion which, when reread, causes the contents of @var{file} to be transparently copied through to the output. In @acronym{UNIX} @code{troff}, the contents of @var{file} is immediately copied through to the output regardless of whether there is a current diversion; this behaviour is so anomalous that it must be considered a bug. @cindex @code{trf} request, and invalid characters @cindex characters, invalid for @code{trf} request @cindex invalid characters for @code{trf} request While @code{cf} copies the contents of @var{file} completely unprocessed, @code{trf} disallows characters such as NUL that are not valid @code{gtroff} input characters (@pxref{Identifiers}). Both requests cause a line break. @endDefreq @Defreq {nx, [@Var{file}]} @cindex processing next file (@code{nx}) @cindex file, processing next (@code{nx}) @cindex next file, processing (@code{nx}) Force @code{gtroff} to continue processing of the file specified as an argument. If no argument is given, immediately jump to the end of file. @endDefreq @Defreq {rd, [@Var{prompt} [@Var{arg1} @Var{arg2} @dots{}]]} @cindex reading from standard input (@code{rd}) @cindex standard input, reading from (@code{rd}) @cindex input, standard, reading from (@code{rd}) Read from standard input, and include what is read as though it were part of the input file. Text is read until a blank line is encountered. If standard input is a TTY input device (keyboard), write @var{prompt} to standard error, followed by a colon (or send BEL for a beep if no argument is given). Arguments after @var{prompt} are available for the input. For example, the line @Example .rd data foo bar @endExample with the input @w{@samp{This is \$2.}} prints @Example This is bar. @endExample @endDefreq @cindex form letters @cindex letters, form Using the @code{nx} and @code{rd} requests, it is easy to set up form letters. The form letter template is constructed like this, putting the following lines into a file called @file{repeat.let}: @Example .ce \*(td .sp 2 .nf .rd .sp .rd .fi Body of letter. .bp .nx repeat.let @endExample @cindex @code{ex} request, used with @code{nx} and @code{rd} @noindent When this is run, a file containing the following lines should be redirected in. Note that requests included in this file are executed as though they were part of the form letter. The last block of input is the @code{ex} request which tells @code{groff} to stop processing. If this was not there, @code{groff} would not know when to stop. @Example Trent A. Fisher 708 NW 19th Av., #202 Portland, OR 97209 Dear Trent, Len Adollar 4315 Sierra Vista San Diego, CA 92103 Dear Mr. Adollar, .ex @endExample @Defreq {pi, pipe} Pipe the output of @code{gtroff} to the shell command(s) specified by @var{pipe}. This request must occur before @code{gtroff} has a chance to print anything. @cindex safer mode @cindex mode, safer @cindex unsafe mode @cindex mode, unsafe @code{pi} causes an error if used in safer mode (which is the default). Use @code{groff}'s or @code{troff}'s @option{-U} option to activate unsafe mode. Multiple calls to @code{pi} are allowed, acting as a chain. For example, @Example .pi foo .pi bar ... @endExample is the same as @w{@samp{.pi foo | bar}}. @cindex @code{groff}, and @code{pi} request @cindex @code{pi} request, and @code{groff} Note that the intermediate output format of @code{gtroff} is piped to the specified commands. Consequently, calling @code{groff} without the @option{-Z} option normally causes a fatal error. @endDefreq @DefreqList {sy, cmds} @DefregListEnd {systat} Execute the shell command(s) specified by @var{cmds}. The output is not saved anyplace, so it is up to the user to do so. @cindex safer mode @cindex mode, safer @cindex unsafe mode @cindex mode, unsafe This request causes an error if used in safer mode (which is the default). Use @code{groff}'s or @code{troff}'s @option{-U} option to activate unsafe mode. For example, the following code fragment introduces the current time into a document: @cindex time, current @cindex current time @pindex perl @Example .sy perl -e 'printf ".nr H %d\\n.nr M %d\\n.nr S %d\\n",\ (localtime(time))[2,1,0]' > /tmp/x\n[$$] .so /tmp/x\n[$$] .sy rm /tmp/x\n[$$] \nH:\nM:\nS @endExample @noindent Note that this works by having the @code{perl} script (run by @code{sy}) print out the @code{nr} requests which set the number registers @code{H}, @code{M}, and @code{S}, and then reads those commands in with the @code{so} request. For most practical purposes, the number registers @code{seconds}, @code{minutes}, and @code{hours} which are initialized at start-up of @code{gtroff} should be sufficient. Use the @code{af} request to get a formatted output: @Example .af hours 00 .af minutes 00 .af seconds 00 \n[hours]:\n[minutes]:\n[seconds] @endExample @cindex @code{system()} return value register (@code{systat}) The @code{systat} read-write number register contains the return value of the @code{system()} function executed by the last @code{sy} request. @endDefreq @DefreqList {open, stream file} @DefreqListEnd {opena, stream file} @cindex opening file (@code{open}) @cindex file, opening (@code{open}) @cindex appending to a file (@code{opena}) @cindex file, appending to (@code{opena}) Open the specified @var{file} for writing and associates the specified @var{stream} with it. The @code{opena} request is like @code{open}, but if the file exists, append to it instead of truncating it. @cindex safer mode @cindex mode, safer @cindex unsafe mode @cindex mode, unsafe Both @code{open} and @code{opena} cause an error if used in safer mode (which is the default). Use @code{groff}'s or @code{troff}'s @option{-U} option to activate unsafe mode. @endDefreq @DefreqList {write, stream data} @DefreqListEnd {writec, stream data} @cindex copy-in mode, and @code{write} requests @cindex mode, copy-in, and @code{write} requests @cindex writing to file (@code{write}) @cindex file, writing to (@code{write}) Write to the file associated with the specified @var{stream}. The stream must previously have been the subject of an open request. The remainder of the line is interpreted as the @code{ds} request reads its second argument: A leading @samp{"} is stripped, and it is read in copy-in mode. The @code{writec} request is like @code{write}, but only @code{write} appends a newline to the data. @endDefreq @Defreq {writem, stream xx} @cindex @code{asciify} request, and @code{writem} Write the contents of the macro or string @var{xx} to the file associated with the specified @var{stream}. @var{xx} is read in copy mode, i.e., already formatted elements are ignored. Consequently, diversions must be unformatted with the @code{asciify} request before calling @code{writem}. Usually, this means a loss of information. @endDefreq @Defreq {close, stream} @cindex closing file (@code{close}) @cindex file, closing (@code{close}) Close the specified @var{stream}; the stream is no longer an acceptable argument to the @code{write} request. Here a simple macro to write an index entry. @Example .open idx test.idx . .de IX . write idx \\n[%] \\$* .. . .IX test entry . .close idx @endExample @endDefreq @DefescList {\\V, , e, } @DefescItem {\\V, @lparen{}, ev, } @DefescListEnd {\\V, @lbrack{}, env, @rbrack} Interpolate the contents of the specified environment variable @var{env} (one-character name@tie{}@var{e}, two-character name @var{ev}) as returned by the function @code{getenv}. @code{\V} is interpreted in copy-in mode. @endDefesc @c ===================================================================== @node Postprocessor Access, Miscellaneous, I/O, gtroff Reference @section Postprocessor Access @cindex postprocessor access @cindex access of postprocessor There are two escapes which give information directly to the postprocessor. This is particularly useful for embedding @sc{PostScript} into the final document. @Defesc {\\X, ', xxx, '} Embeds its argument into the @code{gtroff} output preceded with @w{@samp{x X}}. @cindex @code{\&}, in @code{\X} @cindex @code{\)}, in @code{\X} @cindex @code{\%}, in @code{\X} @ifnotinfo @cindex @code{\:}, in @code{\X} @end ifnotinfo @ifinfo @cindex @code{\@r{}}, in @code{\X} @end ifinfo The escapes @code{\&}, @code{\)}, @code{\%}, and @code{\:} are ignored within @code{\X}, @w{@samp{\ }} and @code{\~} are converted to single space characters. All other escapes (except @code{\\} which produces a backslash) cause an error. @kindex use_charnames_in_special @pindex DESC@r{, and @code{use_charnames_in_special}} @cindex @code{\X}, and special characters If the @samp{use_charnames_in_special} keyword is set in the @file{DESC} file, special characters no longer cause an error; the name @var{xx} is represented as @samp{\(@var{xx})} in the @w{@samp{x X}} output command. Additionally, the backslash is represented as @code{\\}. @samp{use_charnames_in_special} is currently used by @code{grohtml} only. @endDefesc @DefescList {\\Y, , n, } @DefescItem {\\Y, @lparen{}, nm, } @DefescListEnd {\\Y, @lbrack{}, name, @rbrack} This is approximately equivalent to @samp{\X'\*[@var{name}]'} (one-character name@tie{}@var{n}, two-character name @var{nm}). However, the contents of the string or macro @var{name} are not interpreted; also it is permitted for @var{name} to have been defined as a macro and thus contain newlines (it is not permitted for the argument to @code{\X} to contain newlines). The inclusion of newlines requires an extension to the @acronym{UNIX} @code{troff} output format, and confuses drivers that do not know about this extension (@pxref{Device Control Commands}). @endDefesc @xref{Output Devices}. @c ===================================================================== @node Miscellaneous, Gtroff Internals, Postprocessor Access, gtroff Reference @section Miscellaneous This section documents parts of @code{gtroff} which cannot (yet) be categorized elsewhere in this manual. @Defreq {nm, [@Var{start} [@Var{inc} [@Var{space} [@Var{indent}]]]]} @cindex printing line numbers (@code{nm}) @cindex line numbers, printing (@code{nm}) @cindex numbers, line, printing (@code{nm}) Print line numbers. @var{start} is the line number of the @emph{next} output line. @var{inc} indicates which line numbers are printed. For example, the value@tie{}5 means to emit only line numbers which are multiples of@tie{}5; this defaults to@tie{}1. @var{space} is the space to be left between the number and the text; this defaults to one digit space. The fourth argument is the indentation of the line numbers, defaulting to zero. Both @var{space} and @var{indent} are given as multiples of digit spaces; they can be negative also. Without any arguments, line numbers are turned off. @code{gtroff} reserves three digit spaces for the line number (which is printed right-justified) plus the amount given by @var{indent}; the output lines are concatenated to the line numbers, separated by @var{space}, and @emph{without} reducing the line length. Depending on the value of the horizontal page offset (as set with the @code{po} request), line numbers which are longer than the reserved space stick out to the left, or the whole line is moved to the right. Parameters corresponding to missing arguments are not changed; any non-digit argument (to be more precise, any argument starting with a character valid as a delimiter for identifiers) is also treated as missing. If line numbering has been disabled with a call to @code{nm} without an argument, it can be reactivated with @samp{.nm +0}, using the previously active line numbering parameters. The parameters of @code{nm} are associated with the current environment (@pxref{Environments}). The current output line number is available in the number register @code{ln}. @Example .po 1m .ll 2i This test shows how line numbering works with groff. .nm 999 This test shows how line numbering works with groff. .br .nm xxx 3 2 .ll -\w'0'u This test shows how line numbering works with groff. .nn 2 This test shows how line numbering works with groff. @endExample @noindent And here the result: @Example This test shows how line numbering works 999 with groff. This 1000 test shows how line 1001 numbering works with 1002 groff. This test shows how line numbering works with groff. This test shows how 1005 line numbering works with groff. @endExample @endDefreq @Defreq {nn, [@Var{skip}]} Temporarily turn off line numbering. The argument is the number of lines not to be numbered; this defaults to@tie{}1. @endDefreq @Defreq {mc, glyph [@Var{dist}]} @cindex margin glyph (@code{mc}) @cindex glyph, for margins (@code{mc}) Print a @dfn{margin character} to the right of the text.@footnote{@dfn{Margin character} is a misnomer since it is an output glyph.} The first argument is the glyph to be printed. The second argument is the distance away from the right margin. If missing, the previously set value is used; default is 10@dmn{pt}). For text lines that are too long (that is, longer than the text length plus @var{dist}), the margin character is directly appended to the lines. With no arguments the margin character is turned off. If this occurs before a break, no margin character is printed. For compatibility with @acronym{AT&T} @code{troff}, a call to @code{mc} to set the margin character can't be undone immediately; at least one line gets a margin character. Thus @Example .ll 1i .mc \[br] .mc xxx .br xxx @endExample @noindent produces @Example xxx | xxx @endExample @cindex @code{tl} request, and @code{mc} For empty lines and lines produced by the @code{tl} request no margin character is emitted. The margin character is associated with the current environment (@pxref{Environments}). @pindex nrchbar @pindex changebar This is quite useful for indicating text that has changed, and, in fact, there are programs available for doing this (they are called @code{nrchbar} and @code{changebar} and can be found in any @samp{comp.sources.unix} archive). @Example .ll 3i .mc | This paragraph is highlighted with a margin character. .sp Note that vertical space isn't marked. .br \& .br But we can fake it with `\&'. @endExample Result: @Example This paragraph is highlighted | with a margin character. | Note that vertical space isn't | marked. | | But we can fake it with `\&'. | @endExample @endDefreq @DefreqList {psbb, filename} @DefregItem {llx} @DefregItem {lly} @DefregItem {urx} @DefregListEnd {ury} @cindex PostScript, bounding box @cindex bounding box Retrieve the bounding box of the PostScript image found in @var{filename}. The file must conform to Adobe's @dfn{Document Structuring Conventions} (DSC); the command searches for a @code{%%BoundingBox} comment and extracts the bounding box values into the number registers @code{llx}, @code{lly}, @code{urx}, and @code{ury}. If an error occurs (for example, @code{psbb} cannot find the @code{%%BoundingBox} comment), it sets the four number registers to zero. The search path for @var{filename} can be controlled with the @option{-I} command line option. @endDefreq @c ===================================================================== @node Gtroff Internals, Debugging, Miscellaneous, gtroff Reference @section @code{gtroff} Internals @cindex input token @cindex token, input @cindex output node @cindex node, output @code{gtroff} processes input in three steps. One or more input characters are converted to an @dfn{input token}.@footnote{Except the escapes @code{\f}, @code{\F}, @code{\H}, @code{\m}, @code{\M}, @code{\R}, @code{\s}, and @code{\S} which are processed immediately if not in copy-in mode.} Then, one or more input tokens are converted to an @dfn{output node}. Finally, output nodes are converted to the intermediate output language understood by all output devices. Actually, before step one happens, @code{gtroff} converts certain escape sequences into reserved input characters (not accessible by the user); such reserved characters are used for other internal processing also -- this is the very reason why not all characters are valid input. @xref{Identifiers}, for more on this topic. For example, the input string @samp{fi\[:u]} is converted into a character token @samp{f}, a character token @samp{i}, and a special token @samp{:u} (representing u@tie{}umlaut). Later on, the character tokens @samp{f} and @samp{i} are merged to a single output node representing the ligature glyph @samp{fi} (provided the current font has a glyph for this ligature); the same happens with @samp{:u}. All output glyph nodes are `processed' which means that they are invariably associated with a given font, font size, advance width, etc. During the formatting process, @code{gtroff} itself adds various nodes to control the data flow. Macros, diversions, and strings collect elements in two chained lists: a list of input tokens which have been passed unprocessed, and a list of output nodes. Consider the following the diversion. @Example .di xxx a \!b c .br .di @endExample @noindent It contains these elements. @multitable {@i{vertical size node}} {token list} {element number} @item node list @tab token list @tab element number @item @i{line start node} @tab --- @tab 1 @item @i{glyph node @code{a}} @tab --- @tab 2 @item @i{word space node} @tab --- @tab 3 @item --- @tab @code{b} @tab 4 @item --- @tab @code{\n} @tab 5 @item @i{glyph node @code{c}} @tab --- @tab 6 @item @i{vertical size node} @tab --- @tab 7 @item @i{vertical size node} @tab --- @tab 8 @item --- @tab @code{\n} @tab 9 @end multitable @cindex @code{\v}, internal representation @noindent Elements 1, 7, and@tie{}8 are inserted by @code{gtroff}; the latter two (which are always present) specify the vertical extent of the last line, possibly modified by @code{\x}. The @code{br} request finishes the current partial line, inserting a newline input token which is subsequently converted to a space when the diversion is reread. Note that the word space node has a fixed width which isn't stretchable anymore. To convert horizontal space nodes back to input tokens, use the @code{unformat} request. Macros only contain elements in the token list (and the node list is empty); diversions and strings can contain elements in both lists. Note that the @code{chop} request simply reduces the number of elements in a macro, string, or diversion by one. Exceptions are @dfn{compatibility save} and @dfn{compatibility ignore} input tokens which are ignored. The @code{substring} request also ignores those input tokens. Some requests like @code{tr} or @code{cflags} work on glyph identifiers only; this means that the associated glyph can be changed without destroying this association. This can be very helpful for substituting glyphs. In the following example, we assume that glyph @samp{foo} isn't available by default, so we provide a substitution using the @code{fchar} request and map it to input character @samp{x}. @Example .fchar \[foo] foo .tr x \[foo] @endExample @noindent Now let us assume that we install an additional special font @samp{bar} which has glyph @samp{foo}. @Example .special bar .rchar \[foo] @endExample @noindent Since glyphs defined with @code{fchar} are searched before glyphs in special fonts, we must call @code{rchar} to remove the definition of the fallback glyph. Anyway, the translation is still active; @samp{x} now maps to the real glyph @samp{foo}. @c ===================================================================== @node Debugging, Implementation Differences, Gtroff Internals, gtroff Reference @section Debugging @cindex debugging @code{gtroff} is not easy to debug, but there are some useful features and strategies for debugging. @Defreq {lf, line [@Var{filename}]} @pindex soelim @cindex multi-file documents @cindex documents, multi-file @cindex setting input line number (@code{lf}) @cindex input line number, setting (@code{lf}) @cindex number, input line, setting (@code{lf}) Change the line number and optionally the file name @code{gtroff} shall use for error and warning messages. @var{line} is the input line number of the @emph{next} line. Without argument, the request is ignored. This is a debugging aid for documents which are split into many files, then put together with @code{soelim} and other preprocessors. Usually, it isn't invoked manually. Note that other @code{troff} implementations (including the original @acronym{AT&T} version) handle @code{lf} differently. For them, @var{line} changes the line number of the @emph{current} line. @endDefreq @DefreqList {tm, string} @DefreqItem {tm1, string} @DefreqListEnd {tmc, string} @cindex printing to stderr (@code{tm}, @code{tm1}, @code{tmc}) @cindex stderr, printing to (@code{tm}, @code{tm1}, @code{tmc}) Send @var{string} to the standard error output; this is very useful for printing debugging messages among other things. @var{string} is read in copy mode. The @code{tm} request ignores leading spaces of @var{string}; @code{tm1} handles its argument similar to the @code{ds} request: a leading double quote in @var{string} is stripped to allow initial blanks. The @code{tmc} request is similar to @code{tm1} but does not append a newline (as is done in @code{tm} and @code{tm1}). @endDefreq @Defreq {ab, [@Var{string}]} @cindex aborting (@code{ab}) Similar to the @code{tm} request, except that it causes @code{gtroff} to stop processing. With no argument it prints @samp{User Abort.} to standard error. @endDefreq @Defreq {ex, } @cindex @code{ex} request, use in debugging @cindex exiting (@code{ex}) The @code{ex} request also causes @code{gtroff} to stop processing; see also @ref{I/O}. @endDefreq When doing something involved it is useful to leave the debugging statements in the code and have them turned on by a command line flag. @Example .if \n(DB .tm debugging output @endExample @noindent To activate these statements say @Example groff -rDB=1 file @endExample If it is known in advance that there will be many errors and no useful output, @code{gtroff} can be forced to suppress formatted output with the @option{-z} flag. @Defreq {pm, } @cindex dumping symbol table (@code{pm}) @cindex symbol table, dumping (@code{pm}) Print the entire symbol table on @code{stderr}. Names of all defined macros, strings, and diversions are print together with their size in bytes. Since @code{gtroff} sometimes adds nodes by itself, the returned size can be larger than expected. This request differs from @acronym{UNIX} @code{troff}: @code{gtroff} reports the sizes of diversions, ignores an additional argument to print only the total of the sizes, and the size isn't returned in blocks of 128 characters. @endDefreq @Defreq {pnr, } @cindex dumping number registers (@code{pnr}) @cindex number registers, dumping (@code{pnr}) Print the names and contents of all currently defined number registers on @code{stderr}. @endDefreq @Defreq {ptr, } @cindex dumping traps (@code{ptr}) @cindex traps, dumping (@code{ptr}) Print the names and positions of all traps (not including input line traps and diversion traps) on @code{stderr}. Empty slots in the page trap list are printed as well, because they can affect the priority of subsequently planted traps. @endDefreq @Defreq {fl, } @cindex flush output (@code{fl}) @cindex output, flush (@code{fl}) @cindex interactive use of @code{gtroff} @cindex @code{gtroff}, interactive use Instruct @code{gtroff} to flush its output immediately. The intent is for interactive use, but this behaviour is currently not implemented in @code{gtroff}. Contrary to @acronym{UNIX} @code{troff}, TTY output is sent to a device driver also (@code{grotty}), making it non-trivial to communicate interactively. This request causes a line break. @endDefreq @Defreq {backtrace, } @cindex backtrace of input stack (@code{backtrace}) @cindex input stack, backtrace (@code{backtrace}) Print a backtrace of the input stack to the standard error stream. Consider the following in file @file{test}: @Example .de xxx . backtrace .. .de yyy . xxx .. . .yyy @endExample @noindent On execution, @code{gtroff} prints the following: @Example test:2: backtrace: macro `xxx' test:5: backtrace: macro `yyy' test:8: backtrace: file `test' @endExample The option @option{-b} of @code{gtroff} internally calls a variant of this request on each error and warning. @endDefreq @Defreg {slimit} @cindex input stack, setting limit Use the @code{slimit} number register to set the maximum number of objects on the input stack. If @code{slimit} is less than or equal to@tie{}0, there is no limit set. With no limit, a buggy recursive macro can exhaust virtual memory. The default value is 1000; this is a compile-time constant. @endDefreg @Defreq {warnscale, si} Set the scaling indicator used in warnings to @var{si}. Valid values for @var{si} are @samp{u}, @samp{i}, @samp{c}, @samp{p}, and @samp{P}. At startup, it is set to @samp{i}. @endDefreq @Defreq {spreadwarn, [@Var{limit}]} Make @code{gtroff} emit a warning if the additional space inserted for each space between words in an output line is larger or equal to @var{limit}. A negative value is changed to zero; no argument toggles the warning on and off without changing @var{limit}. The default scaling indicator is @samp{m}. At startup, @code{spreadwarn} is deactivated, and @var{limit} is set to 3@dmn{m}. For example, @Example .spreadwarn 0.2m @endExample @noindent will cause a warning if @code{gtroff} must add 0.2@dmn{m} or more for each interword space in a line. This request is active only if text is justified to both margins (using @w{@samp{.ad b}}). @endDefreq @cindex warnings @code{gtroff} has command line options for printing out more warnings (@option{-w}) and for printing backtraces (@option{-b}) when a warning or an error occurs. The most verbose level of warnings is @option{-ww}. @DefreqList {warn, [@Var{flags}]} @DefregListEnd {.warn} @cindex level of warnings (@code{warn}) @cindex warnings, level (@code{warn}) Control the level of warnings checked for. The @var{flags} are the sum of the numbers associated with each warning that is to be enabled; all other warnings are disabled. The number associated with each warning is listed below. For example, @w{@code{.warn 0}} disables all warnings, and @w{@code{.warn 1}} disables all warnings except that about missing glyphs. If no argument is given, all warnings are enabled. The read-only number register @code{.warn} contains the current warning level. @endDefreq @menu * Warnings:: @end menu @c --------------------------------------------------------------------- @node Warnings, , Debugging, Debugging @subsection Warnings @cindex warnings The warnings that can be given to @code{gtroff} are divided into the following categories. The name associated with each warning is used by the @option{-w} and @option{-W} options; the number is used by the @code{warn} request and by the @code{.warn} register. @table @samp @item char @itemx 1 Non-existent glyphs.@footnote{@code{char} is a misnomer since it reports missing glyphs -- there aren't missing input characters, only invalid ones.} This is enabled by default. @item number @itemx 2 Invalid numeric expressions. This is enabled by default. @xref{Expressions}. @item break @itemx 4 @cindex fill mode @cindex mode, fill In fill mode, lines which could not be broken so that their length was less than the line length. This is enabled by default. @item delim @itemx 8 Missing or mismatched closing delimiters. @item el @itemx 16 @cindex @code{ie} request, and warnings @cindex @code{el} request, and warnings Use of the @code{el} request with no matching @code{ie} request. @xref{if-else}. @item scale @itemx 32 Meaningless scaling indicators. @item range @itemx 64 Out of range arguments. @item syntax @itemx 128 Dubious syntax in numeric expressions. @item di @itemx 256 @cindex @code{di} request, and warnings @cindex @code{da} request, and warnings Use of @code{di} or @code{da} without an argument when there is no current diversion. @item mac @itemx 512 @cindex @code{de}, @code{de1}, @code{dei} requests, and warnings @cindex @code{am}, @code{am1}, @code{ami} requests, and warnings @cindex @code{ds}, @code{ds1} requests, and warnings @cindex @code{as}, @code{as1} requests, and warnings @cindex @code{di} request, and warnings @cindex @code{da} request, and warnings @cindex @code{box}, @code{boxa} requests, and warnings @cindex @code{\*}, and warnings Use of undefined strings, macros and diversions. When an undefined string, macro, or diversion is used, that string is automatically defined as empty. So, in most cases, at most one warning is given for each name. @item reg @itemx 1024 @cindex @code{nr} request, and warnings @cindex @code{\R}, and warnings @cindex @code{\n}, and warnings Use of undefined number registers. When an undefined number register is used, that register is automatically defined to have a value of@tie{}0. So, in most cases, at most one warning is given for use of a particular name. @item tab @itemx 2048 @cindex @code{\t}, and warnings Use of a tab character where a number was expected. @item right-brace @itemx 4096 @cindex @code{\@}}, and warnings Use of @code{\@}} where a number was expected. @item missing @itemx 8192 Requests that are missing non-optional arguments. @item input @itemx 16384 Invalid input characters. @item escape @itemx 32768 Unrecognized escape sequences. When an unrecognized escape sequence @code{\@var{X}} is encountered, the escape character is ignored, and @var{X} is printed. @item space @itemx 65536 @cindex compatibility mode Missing space between a request or macro and its argument. This warning is given when an undefined name longer than two characters is encountered, and the first two characters of the name make a defined name. The request or macro is not invoked. When this warning is given, no macro is automatically defined. This is enabled by default. This warning never occurs in compatibility mode. @item font @itemx 131072 Non-existent fonts. This is enabled by default. @item ig @itemx 262144 Invalid escapes in text ignored with the @code{ig} request. These are conditions that are errors when they do not occur in ignored text. @item color @itemx 524288 Color related warnings. @item all All warnings except @samp{di}, @samp{mac} and @samp{reg}. It is intended that this covers all warnings that are useful with traditional macro packages. @item w All warnings. @end table @c ===================================================================== @node Implementation Differences, , Debugging, gtroff Reference @section Implementation Differences @cindex implementation differences @cindex differences in implementation @cindex incompatibilities with @acronym{AT&T} @code{troff} @cindex compatibility mode @cindex mode, compatibility GNU @code{troff} has a number of features which cause incompatibilities with documents written with old versions of @code{troff}. @cindex long names @cindex names, long Long names cause some incompatibilities. @acronym{UNIX} @code{troff} interprets @Example .dsabcd @endExample @cindex @code{\*}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\n}, incompatibilities with @acronym{AT&T} @code{troff} @noindent as defining a string @samp{ab} with contents @samp{cd}. Normally, GNU @code{troff} interprets this as a call of a macro named @code{dsabcd}. Also @acronym{UNIX} @code{troff} interprets @code{\*[} or @code{\n[} as references to a string or number register called @samp{[}. In GNU @code{troff}, however, this is normally interpreted as the start of a long name. In compatibility mode GNU @code{troff} interprets long names in the traditional way (which means that they are not recognized as names). @DefreqList {cp, [@Var{n}]} @DefreqItem {do, cmd} @DefregListEnd {.C} If @var{n} is missing or non-zero, turn on compatibility mode; otherwise, turn it off. The read-only number register @code{.C} is@tie{}1 if compatibility mode is on, 0@tie{}otherwise. Compatibility mode can be also turned on with the @option{-C} command line option. The @code{do} request turns off compatibility mode while executing its arguments as a @code{gtroff} command. @Example .do fam T @endExample @noindent executes the @code{fam} request when compatibility mode is enabled. @code{gtroff} restores the previous compatibility setting before interpreting any files sourced by the @var{cmd}. @endDefreq @cindex input level in delimited arguments @cindex delimited arguments, incompatibilities with @acronym{AT&T} @code{troff} Two other features are controlled by @option{-C}. If not in compatibility mode, GNU @code{troff} preserves the input level in delimited arguments: @Example .ds xx ' \w'abc\*(xxdef' @endExample @noindent In compatibility mode, the string @samp{72def'} is returned; without @option{-C} the resulting string is @samp{168} (assuming a TTY output device). @cindex @code{\f}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\H}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\s}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\S}, incompatibilities with @acronym{AT&T} @code{troff} Finally, the escapes @code{\f}, @code{\H}, @code{\m}, @code{\M}, @code{\R}, @code{\s}, and @code{\S} are transparent for recognizing the beginning of a line only in compatibility mode (this is a rather obscure feature). For example, the code @Example .de xx Hallo! .. \fB.xx\fP @endExample @noindent prints @samp{Hallo!} in bold face if in compatibility mode, and @samp{.xx} in bold face otherwise. @cindex @code{\A}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\|}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\^}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\&}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\@{}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\@}}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\@key{SP}}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\'}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\`}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\-}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\_}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\!}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\%}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\c}, incompatibilities with @acronym{AT&T} @code{troff} GNU @code{troff} does not allow the use of the escape sequences @code{\|}, @code{\^}, @code{\&}, @code{\@{}, @code{\@}}, @code{\@key{SP}}, @code{\'}, @code{\`}, @code{\-}, @code{\_}, @code{\!}, @code{\%}, and @code{\c} in names of strings, macros, diversions, number registers, fonts or environments; @acronym{UNIX} @code{troff} does. The @code{\A} escape sequence (@pxref{Identifiers}) may be helpful in avoiding use of these escape sequences in names. @cindex fractional point sizes @cindex fractional type sizes @cindex point sizes, fractional @cindex type sizes, fractional @cindex sizes, fractional @cindex @code{ps} request, incompatibilities with @acronym{AT&T} @code{troff} Fractional point sizes cause one noteworthy incompatibility. In @acronym{UNIX} @code{troff} the @code{ps} request ignores scale indicators and thus @Example .ps 10u @endExample @noindent sets the point size to 10@tie{}points, whereas in GNU @code{troff} it sets the point size to 10@tie{}scaled points. @xref{Fractional Type Sizes}, for more information. @cindex @code{bd} request, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{cs} request, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{tr} request, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{fp} request, incompatibilities with @acronym{AT&T} @code{troff} @cindex input characters and output glyphs, compatibility with @acronym{AT&T} @code{troff} @cindex output glyphs, and input characters,compatibility with @acronym{AT&T} @code{troff} @cindex characters, input, and output glyphs, compatibility with @acronym{AT&T} @code{troff} @cindex glyphs, output, and input characters, compatibility with @acronym{AT&T} @code{troff} In GNU @code{troff} there is a fundamental difference between (unformatted) input characters and (formatted) output glyphs. Everything that affects how a glyph is output is stored with the glyph node; once a glyph node has been constructed it is unaffected by any subsequent requests that are executed, including @code{bd}, @code{cs}, @code{tkf}, @code{tr}, or @code{fp} requests. Normally glyphs are constructed from input characters at the moment immediately before the glyph is added to the current output line. Macros, diversions and strings are all, in fact, the same type of object; they contain lists of input characters and glyph nodes in any combination. A glyph node does not behave like an input character for the purposes of macro processing; it does not inherit any of the special properties that the input character from which it was constructed might have had. For example, @Example .di x \\\\ .br .di .x @endExample @cindex printing backslash (@code{\\}, @code{\e}, @code{\E}, @code{\[rs]}) @cindex backslash, printing (@code{\\}, @code{\e}, @code{\E}, @code{\[rs]}) @cindex @code{\e}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\!}, incompatibilities with @acronym{AT&T} @code{troff} @cindex @code{\?}, incompatibilities with @acronym{AT&T} @code{troff} @cindex transparent output, incompatibilities with @acronym{AT&T} @code{troff} @cindex output, transparent, incompatibilities with @acronym{AT&T} @code{troff} @noindent prints @samp{\\} in GNU @code{troff}; each pair of input backslashes is turned into one output backslash and the resulting output backslashes are not interpreted as escape characters when they are reread. @acronym{UNIX} @code{troff} would interpret them as escape characters when they were reread and would end up printing one @samp{\}. The correct way to obtain a printable backslash is to use the @code{\e} escape sequence: This always prints a single instance of the current escape character, regardless of whether or not it is used in a diversion; it also works in both GNU @code{troff} and @acronym{UNIX} @code{troff}.@footnote{To be completely independent of the current escape character, use @code{\(rs} which represents a reverse solidus (backslash) glyph.} To store, for some reason, an escape sequence in a diversion that will be interpreted when the diversion is reread, either use the traditional @code{\!} transparent output facility, or, if this is unsuitable, the new @code{\?} escape sequence. @xref{Diversions}, and @ref{Gtroff Internals}, for more information. @c ===================================================================== @c ===================================================================== @node Preprocessors, Output Devices, gtroff Reference, Top @chapter Preprocessors @cindex preprocessors This chapter describes all preprocessors that come with @code{groff} or which are freely available. @menu * geqn:: * gtbl:: * gpic:: * ggrn:: * grap:: * grefer:: * gsoelim:: @end menu @c ===================================================================== @node geqn, gtbl, Preprocessors, Preprocessors @section @code{geqn} @cindex @code{eqn}, the program @cindex @code{geqn}, the program @c XXX @menu * Invoking geqn:: @end menu @c --------------------------------------------------------------------- @node Invoking geqn, , geqn, geqn @subsection Invoking @code{geqn} @cindex invoking @code{geqn} @cindex @code{geqn}, invoking @c XXX @c ===================================================================== @node gtbl, gpic, geqn, Preprocessors @section @code{gtbl} @cindex @code{tbl}, the program @cindex @code{gtbl}, the program @c XXX @menu * Invoking gtbl:: @end menu @c --------------------------------------------------------------------- @node Invoking gtbl, , gtbl, gtbl @subsection Invoking @code{gtbl} @cindex invoking @code{gtbl} @cindex @code{gtbl}, invoking @c XXX @c ===================================================================== @node gpic, ggrn, gtbl, Preprocessors @section @code{gpic} @cindex @code{pic}, the program @cindex @code{gpic}, the program @c XXX @menu * Invoking gpic:: @end menu @c --------------------------------------------------------------------- @node Invoking gpic, , gpic, gpic @subsection Invoking @code{gpic} @cindex invoking @code{gpic} @cindex @code{gpic}, invoking @c XXX @c ===================================================================== @node ggrn, grap, gpic, Preprocessors @section @code{ggrn} @cindex @code{grn}, the program @cindex @code{ggrn}, the program @c XXX @menu * Invoking ggrn:: @end menu @c --------------------------------------------------------------------- @node Invoking ggrn, , ggrn, ggrn @subsection Invoking @code{ggrn} @cindex invoking @code{ggrn} @cindex @code{ggrn}, invoking @c XXX @c ===================================================================== @node grap, grefer, ggrn, Preprocessors @section @code{grap} @cindex @code{grap}, the program A free implementation of @code{grap}, written by Ted Faber, is available as an extra package from the following address: @display @uref{http://www.lunabase.org/~faber/Vault/software/grap/} @end display @c ===================================================================== @node grefer, gsoelim, grap, Preprocessors @section @code{grefer} @cindex @code{refer}, the program @cindex @code{grefer}, the program @c XXX @menu * Invoking grefer:: @end menu @c --------------------------------------------------------------------- @node Invoking grefer, , grefer, grefer @subsection Invoking @code{grefer} @cindex invoking @code{grefer} @cindex @code{grefer}, invoking @c XXX @c ===================================================================== @node gsoelim, , grefer, Preprocessors @section @code{gsoelim} @cindex @code{soelim}, the program @cindex @code{gsoelim}, the program @c XXX @menu * Invoking gsoelim:: @end menu @c --------------------------------------------------------------------- @node Invoking gsoelim, , gsoelim, gsoelim @subsection Invoking @code{gsoelim} @cindex invoking @code{gsoelim} @cindex @code{gsoelim}, invoking @c XXX @c ===================================================================== @c ===================================================================== @node Output Devices, File formats, Preprocessors, Top @chapter Output Devices @cindex output devices @cindex devices for output @c XXX @menu * Special Characters:: * grotty:: * grops:: * grodvi:: * grolj4:: * grolbp:: * grohtml:: * gxditview:: @end menu @c ===================================================================== @node Special Characters, grotty, Output Devices, Output Devices @section Special Characters @cindex special characters @cindex characters, special @c XXX @xref{Font Files}. @c ===================================================================== @node grotty, grops, Special Characters, Output Devices @section @code{grotty} @cindex @code{grotty}, the program @c XXX @menu * Invoking grotty:: @end menu @c --------------------------------------------------------------------- @node Invoking grotty, , grotty, grotty @subsection Invoking @code{grotty} @cindex invoking @code{grotty} @cindex @code{grotty}, invoking @c XXX @c The following is no longer true; fix and extend it. @c @pindex less @c @cindex Teletype @c @cindex ISO 6249 SGR @c @cindex terminal control sequences @c @cindex control sequences, for terminals @c For TTY output devices, underlining is done by emitting sequences of @c @samp{_} and @samp{\b} (the backspace character) before the actual @c character. Literally, this is printing an underline character, then @c moving back one character position, and printing the actual character @c at the same position as the underline character (similar to a @c typewriter). Usually, a modern terminal can't interpret this (and the @c original Teletype machines for which this sequence was appropriate are @c no longer in use). You need a pager program like @code{less} which @c translates this into ISO 6429 SGR sequences to control terminals. @c ===================================================================== @node grops, grodvi, grotty, Output Devices @section @code{grops} @cindex @code{grops}, the program @c XXX @menu * Invoking grops:: * Embedding PostScript:: @end menu @c --------------------------------------------------------------------- @node Invoking grops, Embedding PostScript, grops, grops @subsection Invoking @code{grops} @cindex invoking @code{grops} @cindex @code{grops}, invoking @c XXX @c --------------------------------------------------------------------- @node Embedding PostScript, , Invoking grops, grops @subsection Embedding @sc{PostScript} @cindex embedding PostScript @cindex PostScript, embedding @c XXX @c ===================================================================== @node grodvi, grolj4, grops, Output Devices @section @code{grodvi} @cindex @code{grodvi}, the program @c XXX @menu * Invoking grodvi:: @end menu @c --------------------------------------------------------------------- @node Invoking grodvi, , grodvi, grodvi @subsection Invoking @code{grodvi} @cindex invoking @code{grodvi} @cindex @code{grodvi}, invoking @c XXX @c ===================================================================== @node grolj4, grolbp, grodvi, Output Devices @section @code{grolj4} @cindex @code{grolj4}, the program @c XXX @menu * Invoking grolj4:: @end menu @c --------------------------------------------------------------------- @node Invoking grolj4, , grolj4, grolj4 @subsection Invoking @code{grolj4} @cindex invoking @code{grolj4} @cindex @code{grolj4}, invoking @c XXX @c ===================================================================== @node grolbp, grohtml, grolj4, Output Devices @section @code{grolbp} @cindex @code{grolbp}, the program @c XXX @menu * Invoking grolbp:: @end menu @c --------------------------------------------------------------------- @node Invoking grolbp, , grolbp, grolbp @subsection Invoking @code{grolbp} @cindex invoking @code{grolbp} @cindex @code{grolbp}, invoking @c XXX @c ===================================================================== @node grohtml, gxditview, grolbp, Output Devices @section @code{grohtml} @cindex @code{grohtml}, the program @c XXX @menu * Invoking grohtml:: * grohtml specific registers and strings:: @end menu @c --------------------------------------------------------------------- @node Invoking grohtml, grohtml specific registers and strings, grohtml, grohtml @subsection Invoking @code{grohtml} @cindex invoking @code{grohtml} @cindex @code{grohtml}, invoking @c XXX @c --------------------------------------------------------------------- @node grohtml specific registers and strings, , Invoking grohtml, grohtml @subsection @code{grohtml} specific registers and strings @cindex registers specific to @code{grohtml} @cindex strings specific to @code{grohtml} @cindex @code{grohtml}, registers and strings @DefmpregList {ps4html, grohtml} @DefstrListEnd {www-image-template, grohtml} The registers @code{ps4html} and @code{www-image-template} are defined by the @code{pre-grohtml} preprocessor. @code{pre-grohtml} reads in the @code{troff} input, marks up the inline equations and passes the result firstly to @Example troff -Tps -rps4html=1 -dwww-image-template=@var{template} @endExample @noindent and secondly to @Example troff -Thtml @endExample The PostScript device is used to create all the image files, and the register @code{ps4html} enables the macro sets to ignore floating keeps, footers, and headings. The register @code{www-image-template} is set to the user specified template name or the default name. @endDefmpreg @c ===================================================================== @node gxditview, , grohtml, Output Devices @section @code{gxditview} @cindex @code{gxditview}, the program @c XXX @menu * Invoking gxditview:: @end menu @c --------------------------------------------------------------------- @node Invoking gxditview, , gxditview, gxditview @subsection Invoking @code{gxditview} @cindex invoking @code{gxditview} @cindex @code{gxditview}, invoking @c XXX @c X11's xditview @c ===================================================================== @c ===================================================================== @node File formats, Installation, Output Devices, Top @chapter File formats @cindex file formats @cindex formats, file All files read and written by @code{gtroff} are text files. The following two sections describe their format. @menu * gtroff Output:: * Font Files:: @end menu @c ===================================================================== @node gtroff Output, Font Files, File formats, File formats @section @code{gtroff} Output @cindex @code{gtroff}, output @cindex output, @code{gtroff} This section describes the intermediate output format of GNU @code{troff}. This output is produced by a run of @code{gtroff} before it is fed into a device postprocessor program. As @code{groff} is a wrapper program around @code{gtroff} that automatically calls a postprocessor, this output does not show up normally. This is why it is called @dfn{intermediate}. @code{groff} provides the option @option{-Z} to inhibit postprocessing, such that the produced intermediate output is sent to standard output just like calling @code{gtroff} manually. @cindex troff output @cindex output, troff @cindex intermediate output @cindex output, intermediate Here, the term @dfn{troff output} describes what is output by @code{gtroff}, while @dfn{intermediate output} refers to the language that is accepted by the parser that prepares this output for the postprocessors. This parser is smarter on whitespace and implements obsolete elements for compatibility, otherwise both formats are the same.@footnote{The parser and postprocessor for intermediate output can be found in the file@* @file{@var{groff-source-dir}/src/libs/libdriver/input.cpp}.} The main purpose of the intermediate output concept is to facilitate the development of postprocessors by providing a common programming interface for all devices. It has a language of its own that is completely different from the @code{gtroff} language. While the @code{gtroff} language is a high-level programming language for text processing, the intermediate output language is a kind of low-level assembler language by specifying all positions on the page for writing and drawing. The intermediate output produced by @code{gtroff} is fairly readable, while output from @acronym{AT&T} @code{troff} is rather hard to understand because of strange habits that are still supported, but not used any longer by @code{gtroff}. @menu * Language Concepts:: * Command Reference:: * Intermediate Output Examples:: * Output Language Compatibility:: @end menu @c --------------------------------------------------------------------- @node Language Concepts, Command Reference, gtroff Output, gtroff Output @subsection Language Concepts During the run of @code{gtroff}, the input data is cracked down to the information on what has to be printed at what position on the intended device. So the language of the intermediate output format can be quite small. Its only elements are commands with and without arguments. In this section, the term @dfn{command} always refers to the intermediate output language, and never to the @code{gtroff} language used for document formatting. There are commands for positioning and text writing, for drawing, and for device controlling. @menu * Separation:: * Argument Units:: * Document Parts:: @end menu @node Separation, Argument Units, Language Concepts, Language Concepts @subsubsection Separation @acronym{AT&T} @code{troff} output has strange requirements on whitespace. The @code{gtroff} output parser, however, is smart about whitespace by making it maximally optional. The whitespace characters, i.e., the tab, space, and newline characters, always have a syntactical meaning. They are never printable because spacing within the output is always done by positioning commands. Any sequence of space or tab characters is treated as a single @dfn{syntactical space}. It separates commands and arguments, but is only required when there would occur a clashing between the command code and the arguments without the space. Most often, this happens when variable-length command names, arguments, argument lists, or command clusters meet. Commands and arguments with a known, fixed length need not be separated by syntactical space. A line break is a syntactical element, too. Every command argument can be followed by whitespace, a comment, or a newline character. Thus a @dfn{syntactical line break} is defined to consist of optional syntactical space that is optionally followed by a comment, and a newline character. The normal commands, those for positioning and text, consist of a single letter taking a fixed number of arguments. For historical reasons, the parser allows to stack such commands on the same line, but fortunately, in @code{gtroff}'s intermediate output, every command with at least one argument is followed by a line break, thus providing excellent readability. The other commands -- those for drawing and device controlling -- have a more complicated structure; some recognize long command names, and some take a variable number of arguments. So all @samp{D} and @samp{x} commands were designed to request a syntactical line break after their last argument. Only one command, @w{@samp{x X}}, has an argument that can stretch over several lines; all other commands must have all of their arguments on the same line as the command, i.e., the arguments may not be splitted by a line break. Empty lines (these are lines containing only space and/or a comment), can occur everywhere. They are just ignored. @node Argument Units, Document Parts, Separation, Language Concepts @subsubsection Argument Units Some commands take integer arguments that are assumed to represent values in a measurement unit, but the letter for the corresponding scale indicator is not written with the output command arguments. Most commands assume the scale indicator @samp{u}, the basic unit of the device, some use @samp{z}, the scaled point unit of the device, while others, such as the color commands, expect plain integers. Note that single characters can have the eighth bit set, as can the names of fonts and special characters. The names of characters and fonts can be of arbitrary length. A character that is to be printed will always be in the current font. A string argument is always terminated by the next whitespace character (space, tab, or newline); an embedded @samp{#} character is regarded as part of the argument, not as the beginning of a comment command. An integer argument is already terminated by the next non-digit character, which then is regarded as the first character of the next argument or command. @node Document Parts, , Argument Units, Language Concepts @subsubsection Document Parts A correct intermediate output document consists of two parts, the @dfn{prologue} and the @dfn{body}. The task of the prologue is to set the general device parameters using three exactly specified commands. @code{gtroff}'s prologue is guaranteed to consist of the following three lines (in that order): @Example x T @var{device} x res @var{n} @var{h} @var{v} x init @endExample @noindent with the arguments set as outlined in @ref{Device Control Commands}. Note that the parser for the intermediate output format is able to swallow additional whitespace and comments as well even in the prologue. The body is the main section for processing the document data. Syntactically, it is a sequence of any commands different from the ones used in the prologue. Processing is terminated as soon as the first @w{@samp{x stop}} command is encountered; the last line of any @code{gtroff} intermediate output always contains such a command. Semantically, the body is page oriented. A new page is started by a @samp{p} command. Positioning, writing, and drawing commands are always done within the current page, so they cannot occur before the first @samp{p} command. Absolute positioning (by the @samp{H} and @samp{V} commands) is done relative to the current page; all other positioning is done relative to the current location within this page. @c --------------------------------------------------------------------- @node Command Reference, Intermediate Output Examples, Language Concepts, gtroff Output @subsection Command Reference This section describes all intermediate output commands, both from @acronym{AT&T} @code{troff} as well as the @code{gtroff} extensions. @menu * Comment Command:: * Simple Commands:: * Graphics Commands:: * Device Control Commands:: * Obsolete Command:: @end menu @node Comment Command, Simple Commands, Command Reference, Command Reference @subsubsection Comment Command @table @code @item #@var{anything}@angles{end of line} A comment. Ignore any characters from the @samp{#} character up to the next newline character. This command is the only possibility for commenting in the intermediate output. Each comment can be preceded by arbitrary syntactical space; every command can be terminated by a comment. @end table @node Simple Commands, Graphics Commands, Comment Command, Command Reference @subsubsection Simple Commands The commands in this subsection have a command code consisting of a single character, taking a fixed number of arguments. Most of them are commands for positioning and text writing. These commands are smart about whitespace. Optionally, syntactical space can be inserted before, after, and between the command letter and its arguments. All of these commands are stackable, i.e., they can be preceded by other simple commands or followed by arbitrary other commands on the same line. A separating syntactical space is only necessary when two integer arguments would clash or if the preceding argument ends with a string argument. @table @code @ignore .if (\n[@USE_ENV_STACK] == 1) \{\ .command { Open a new environment by copying the actual device configuration data to the environment stack. . The current environment is setup by the device specification and manipulated by the setting commands. . . .command } Close the actual environment (opened by a preceding .BR { \~command) and restore the previous environment from the environment stack as the actual device configuration data. . \} \" endif @USE_ENV_STACK @end ignore @item C @var{xxx}@angles{whitespace} Print a special character named @var{xxx}. The trailing syntactical space or line break is necessary to allow glyph names of arbitrary length. The glyph is printed at the current print position; the glyph's size is read from the font file. The print position is not changed. @item c @var{g} Print glyph@tie{}@var{g} at the current print position;@footnote{@samp{c} is actually a misnomer since it outputs a glyph.} the glyph's size is read from the font file. The print position is not changed. @item f @var{n} Set font to font number@tie{}@var{n} (a non-negative integer). @item H @var{n} Move right to the absolute vertical position@tie{}@var{n} (a non-negative integer in basic units @samp{u} relative to left edge of current page. @item h @var{n} Move @var{n} (a non-negative integer) basic units @samp{u} horizontally to the right. The original @acronym{UNIX} troff manual allows negative values for @var{n} also, but @code{gtroff} doesn't use this. @item m @var{color-scheme} @r{[}@var{component} @dots{}@r{]} Set the color for text (glyphs), line drawing, and the outline of graphic objects using different color schemes; the analoguous command for the filling color of graphic objects is @samp{DF}. The color components are specified as integer arguments between 0 and 65536. The number of color components and their meaning vary for the different color schemes. These commands are generated by @code{gtroff}'s escape sequence @code{\m}. No position changing. These commands are a @code{gtroff} extension. @table @code @item mc @var{cyan} @var{magenta} @var{yellow} Set color using the CMY color scheme, having the 3@tie{}color components @var{cyan}, @var{magenta}, and @var{yellow}. @item md Set color to the default color value (black in most cases). No component arguments. @item mg @var{gray} Set color to the shade of gray given by the argument, an integer between 0 (black) and 65536 (white). @item mk @var{cyan} @var{magenta} @var{yellow} @var{black} Set color using the CMYK color scheme, having the 4@tie{}color components @var{cyan}, @var{magenta}, @var{yellow}, and @var{black}. @item mr @var{red} @var{green} @var{blue} Set color using the RGB color scheme, having the 3@tie{}color components @var{red}, @var{green}, and @var{blue}. @end table @item N @var{n} Print glyph with index@tie{}@var{n} (a non-negative integer) of the current font. This command is a @code{gtroff} extension. @item n @var{b} @var{a} Inform the device about a line break, but no positioning is done by this command. In @acronym{AT&T} @code{troff}, the integer arguments @var{b} and@tie{}@var{a} informed about the space before and after the current line to make the intermediate output more human readable without performing any action. In @code{groff}, they are just ignored, but they must be provided for compatibility reasons. @item p @var{n} Begin a new page in the outprint. The page number is set to@tie{}@var{n}. This page is completely independent of pages formerly processed even if those have the same page number. The vertical position on the outprint is automatically set to@tie{}0. All positioning, writing, and drawing is always done relative to a page, so a @samp{p} command must be issued before any of these commands. @item s @var{n} Set point size to @var{n}@tie{}scaled points (this is unit @samp{z}). @acronym{AT&T} @code{troff} used the unit points (@samp{p}) instead. @xref{Output Language Compatibility}. @item t @var{xxx}@angles{whitespace} @itemx t @var{xxx} @var{dummy-arg}@angles{whitespace} Print a word, i.e., a sequence of characters @var{xxx} representing output glyphs which names are single characters, terminated by a space character or a line break; an optional second integer argument is ignored (this allows the formatter to generate an even number of arguments). The first glyph should be printed at the current position, the current horizontal position should then be increased by the width of the first glyph, and so on for each glyph. The widths of the glyphs are read from the font file, scaled for the current point size, and rounded to a multiple of the horizontal resolution. Special characters cannot be printed using this command (use the @samp{C} command for special characters). This command is a @code{gtroff} extension; it is only used for devices whose @file{DESC} file contains the @code{tcommand} keyword (@pxref{DESC File Format}). @item u @var{n} @var{xxx}@angles{whitespace} Print word with track kerning. This is the same as the @samp{t} command except that after printing each glyph, the current horizontal position is increased by the sum of the width of that glyph and@tie{}@var{n} (an integer in basic units @samp{u}). This command is a @code{gtroff} extension; it is only used for devices whose @file{DESC} file contains the @code{tcommand} keyword (@pxref{DESC File Format}). @item V @var{n} Move down to the absolute vertical position@tie{}@var{n} (a non-negative integer in basic units @samp{u}) relative to upper edge of current page. @item v @var{n} Move @var{n}@tie{}basic units @samp{u} down (@var{n} is a non-negative integer). The original @acronym{UNIX} troff manual allows negative values for @var{n} also, but @code{gtroff} doesn't use this. @item w Informs about a paddable white space to increase readability. The spacing itself must be performed explicitly by a move command. @end table @node Graphics Commands, Device Control Commands, Simple Commands, Command Reference @subsubsection Graphics Commands Each graphics or drawing command in the intermediate output starts with the letter @samp{D}, followed by one or two characters that specify a subcommand; this is followed by a fixed or variable number of integer arguments that are separated by a single space character. A @samp{D} command may not be followed by another command on the same line (apart from a comment), so each @samp{D} command is terminated by a syntactical line break. @code{gtroff} output follows the classical spacing rules (no space between command and subcommand, all arguments are preceded by a single space character), but the parser allows optional space between the command letters and makes the space before the first argument optional. As usual, each space can be any sequence of tab and space characters. Some graphics commands can take a variable number of arguments. In this case, they are integers representing a size measured in basic units @samp{u}. The arguments called @var{h1}, @var{h2}, @dots{}, @var{hn} stand for horizontal distances where positive means right, negative left. The arguments called @var{v1}, @var{v2}, @dots{}, @var{vn} stand for vertical distances where positive means down, negative up. All these distances are offsets relative to the current location. Each graphics command directly corresponds to a similar @code{gtroff} @code{\D} escape sequence. @xref{Drawing Requests}. Unknown @samp{D} commands are assumed to be device-specific. Its arguments are parsed as strings; the whole information is then sent to the postprocessor. In the following command reference, the syntax element @angles{line break} means a syntactical line break as defined above. @table @code @item D~ @var{h1} @var{v1} @var{h2} @var{v2} @dots{} @var{hn} @var{vn}@angles{line break} Draw B-spline from current position to offset (@var{h1},@var{v1}), then to offset (@var{h2},@var{v2}), if given, etc.@: up to (@var{hn},@var{vn}). This command takes a variable number of argument pairs; the current position is moved to the terminal point of the drawn curve. @item Da @var{h1} @var{v1} @var{h2} @var{v2}@angles{line break} Draw arc from current position to (@var{h1},@var{v1})@math{+}(@var{h2},@var{v2}) with center at (@var{h1},@var{v1}); then move the current position to the final point of the arc. @item DC @var{d}@angles{line break} @itemx DC @var{d} @var{dummy-arg}@angles{line break} Draw a solid circle using the current fill color with diameter@tie{}@var{d} (integer in basic units @samp{u}) with leftmost point at the current position; then move the current position to the rightmost point of the circle. An optional second integer argument is ignored (this allows the formatter to generate an even number of arguments). This command is a @code{gtroff} extension. @item Dc @var{d}@angles{line break} Draw circle line with diameter@tie{}@var{d} (integer in basic units @samp{u}) with leftmost point at the current position; then move the current position to the rightmost point of the circle. @item DE @var{h} @var{v}@angles{line break} Draw a solid ellipse in the current fill color with a horizontal diameter of@tie{}@var{h} and a vertical diameter of@tie{}@var{v} (both integers in basic units @samp{u}) with the leftmost point at the current position; then move to the rightmost point of the ellipse. This command is a @code{gtroff} extension. @item De @var{h} @var{v}@angles{line break} Draw an outlined ellipse with a horizontal diameter of@tie{}@var{h} and a vertical diameter of@tie{}@var{v} (both integers in basic units @samp{u}) with the leftmost point at current position; then move to the rightmost point of the ellipse. @item DF @var{color-scheme} @r{[}@var{component} @dots{}@r{]}@angles{line break} Set fill color for solid drawing objects using different color schemes; the analoguous command for setting the color of text, line graphics, and the outline of graphic objects is @samp{m}. The color components are specified as integer arguments between 0 and 65536. The number of color components and their meaning vary for the different color schemes. These commands are generated by @code{gtroff}'s escape sequences @w{@code{\D'F @dots{}'}} and @code{\M} (with no other corresponding graphics commands). No position changing. This command is a @code{gtroff} extension. @table @code @item DFc @var{cyan} @var{magenta} @var{yellow}@angles{line break} Set fill color for solid drawing objects using the CMY color scheme, having the 3@tie{}color components @var{cyan}, @var{magenta}, and @var{yellow}. @item DFd@angles{line break} Set fill color for solid drawing objects to the default fill color value (black in most cases). No component arguments. @item DFg @var{gray}@angles{line break} Set fill color for solid drawing objects to the shade of gray given by the argument, an integer between 0 (black) and 65536 (white). @item DFk @var{cyan} @var{magenta} @var{yellow} @var{black}@angles{line break} Set fill color for solid drawing objects using the CMYK color scheme, having the 4@tie{}color components @var{cyan}, @var{magenta}, @var{yellow}, and @var{black}. @item DFr @var{red} @var{green} @var{blue}@angles{line break} Set fill color for solid drawing objects using the RGB color scheme, having the 3@tie{}color components @var{red}, @var{green}, and @var{blue}. @end table @item Df @var{n}@angles{line break} The argument@tie{}@var{n} must be an integer in the range @math{-32767} to 32767. @table @asis @item @math{0 @LE @var{n} @LE 1000} Set the color for filling solid drawing objects to a shade of gray, where 0 corresponds to solid white, 1000 (the default) to solid black, and values in between to intermediate shades of gray; this is obsoleted by command @samp{DFg}. @item @math{@var{n} < 0} or @math{@var{n} > 1000} Set the filling color to the color that is currently being used for the text and the outline, see command @samp{m}. For example, the command sequence @Example mg 0 0 65536 Df -1 @endExample @noindent sets all colors to blue. @end table @noindent No position changing. This command is a @code{gtroff} extension. @item Dl @var{h} @var{v}@angles{line break} Draw line from current position to offset (@var{h},@var{v}) (integers in basic units @samp{u}); then set current position to the end of the drawn line. @item Dp @var{h1} @var{v1} @var{h2} @var{v2} @dots{} @var{hn} @var{vn}@angles{line break} Draw a polygon line from current position to offset (@var{h1},@var{v1}), from there to offset (@var{h2},@var{v2}), etc.@: up to offset (@var{hn},@var{vn}), and from there back to the starting position. For historical reasons, the position is changed by adding the sum of all arguments with odd index to the actual horizontal position and the even ones to the vertical position. Although this doesn't make sense it is kept for compatibility. @ignore As the polygon is closed, the end of drawing is the starting point, so the position doesn't change. @end ignore This command is a @code{gtroff} extension. @item Dp @var{h1} @var{v1} @var{h2} @var{v2} @dots{} @var{hn} @var{vn}@angles{line break} Draw a solid polygon in the current fill color rather than an outlined polygon, using the same arguments and positioning as the corresponding @samp{Dp} command. @ignore No position changing. @end ignore This command is a @code{gtroff} extension. @item Dt @var{n}@angles{line break} Set the current line thickness to@tie{}@var{n} (an integer in basic units @samp{u}) if @math{@var{n}>0}; if @math{@var{n}=0} select the smallest available line thickness; if @math{@var{n}<0} set the line thickness proportional to the point size (this is the default before the first @samp{Dt} command was specified). For historical reasons, the horizontal position is changed by adding the argument to the actual horizontal position, while the vertical position is not changed. Although this doesn't make sense it is kept for compatibility. @ignore No position changing. @end ignore This command is a @code{gtroff} extension. @end table @node Device Control Commands, Obsolete Command, Graphics Commands, Command Reference @subsubsection Device Control Commands Each device control command starts with the letter @samp{x}, followed by a space character (optional or arbitrary space or tab in @code{gtroff}) and a subcommand letter or word; each argument (if any) must be preceded by a syntactical space. All @samp{x} commands are terminated by a syntactical line break; no device control command can be followed by another command on the same line (except a comment). The subcommand is basically a single letter, but to increase readability, it can be written as a word, i.e., an arbitrary sequence of characters terminated by the next tab, space, or newline character. All characters of the subcommand word but the first are simply ignored. For example, @code{gtroff} outputs the initialization command @w{@samp{x i}} as @w{@samp{x init}} and the resolution command @w{@samp{x r}} as @w{@samp{x res}}. In the following, the syntax element @angles{line break} means a syntactical line break (@pxref{Separation}). @table @code @item xF @var{name}@angles{line break} The @samp{F} stands for @var{Filename}. Use @var{name} as the intended name for the current file in error reports. This is useful for remembering the original file name when @code{gtroff} uses an internal piping mechanism. The input file is not changed by this command. This command is a @code{gtroff} extension. @item xf @var{n} @var{s}@angles{line break} The @samp{f} stands for @var{font}. Mount font position@tie{}@var{n} (a non-negative integer) with font named@tie{}@var{s} (a text word). @xref{Font Positions}. @item xH @var{n}@angles{line break} The @samp{H} stands for @var{Height}. Set glyph height to@tie{}@var{n} (a positive integer in scaled points @samp{z}). @acronym{AT&T} @code{troff} uses the unit points (@samp{p}) instead. @xref{Output Language Compatibility}. @item xi@angles{line break} The @samp{i} stands for @var{init}. Initialize device. This is the third command of the prologue. @item xp@angles{line break} The @samp{p} stands for @var{pause}. Parsed but ignored. The original @acronym{UNIX} troff manual writes @display pause device, can be restarted @end display @item xr @var{n} @var{h} @var{v}@angles{line break} The @samp{r} stands for @var{resolution}. Resolution is@tie{}@var{n}, while @var{h} is the minimal horizontal motion, and @var{v} the minimal vertical motion possible with this device; all arguments are positive integers in basic units @samp{u} per inch. This is the second command of the prologue. @item xS @var{n}@angles{line break} The @samp{S} stands for @var{Slant}. Set slant to@tie{}@var{n} (an integer in basic units @samp{u}). @item xs@angles{line break} The @samp{s} stands for @var{stop}. Terminates the processing of the current file; issued as the last command of any intermediate troff output. @item xt@angles{line break} The @samp{t} stands for @var{trailer}. Generate trailer information, if any. In @var{gtroff}, this is actually just ignored. @item xT @var{xxx}@angles{line break} The @samp{T} stands for @var{Typesetter}. Set name of device to word @var{xxx}, a sequence of characters ended by the next white space character. The possible device names coincide with those from the @code{groff} @option{-T} option. This is the first command of the prologue. @item xu @var{n}@angles{line break} The @samp{u} stands for @var{underline}. Configure underlining of spaces. If @var{n} is@tie{}1, start underlining of spaces; if @var{n} is@tie{}0, stop underlining of spaces. This is needed for the @code{cu} request in nroff mode and is ignored otherwise. This command is a @code{gtroff} extension. @item xX @var{anything}@angles{line break} The @samp{x} stands for @var{X-escape}. Send string @var{anything} uninterpreted to the device. If the line following this command starts with a @samp{+} character this line is interpreted as a continuation line in the following sense. The @samp{+} is ignored, but a newline character is sent instead to the device, the rest of the line is sent uninterpreted. The same applies to all following lines until the first character of a line is not a @samp{+} character. This command is generated by the @code{gtroff} escape sequence @code{\X}. The line-continuing feature is a @code{gtroff} extension. @end table @node Obsolete Command, , Device Control Commands, Command Reference @subsubsection Obsolete Command In @acronym{AT&T} @code{troff} output, the writing of a single glyph is mostly done by a very strange command that combines a horizontal move and a single character giving the glyph name. It doesn't have a command code, but is represented by a 3-character argument consisting of exactly 2@tie{}digits and a character. @table @asis @item @var{dd}@var{g} Move right @var{dd} (exactly two decimal digits) basic units @samp{u}, then print glyph@tie{}@var{g} (represented as a single character). In @code{gtroff}, arbitrary syntactical space around and within this command is allowed to be added. Only when a preceding command on the same line ends with an argument of variable length a separating space is obligatory. In @acronym{AT&T} @code{troff}, large clusters of these and other commands are used, mostly without spaces; this made such output almost unreadable. @end table For modern high-resolution devices, this command does not make sense because the width of the glyphs can become much larger than two decimal digits. In @code{gtroff}, this is only used for the devices @code{X75}, @code{X75-12}, @code{X100}, and @code{X100-12}. For other devices, the commands @samp{t} and @samp{u} provide a better functionality. @c --------------------------------------------------------------------- @node Intermediate Output Examples, Output Language Compatibility, Command Reference, gtroff Output @subsection Intermediate Output Examples This section presents the intermediate output generated from the same input for three different devices. The input is the sentence @samp{hell world} fed into @code{gtroff} on the command line. @table @asis @item High-resolution device @code{ps} This is the standard output of @code{gtroff} if no @option{-T} option is given. @example @group shell> echo "hell world" | groff -Z -T ps x T ps x res 72000 1 1 x init @end group p1 x font 5 TR f5 s10000 V12000 H72000 thell wh2500 tw H96620 torld n12000 0 @group x trailer V792000 x stop @end group @end example @noindent This output can be fed into @code{grops} to get its representation as a PostScript file. @item Low-resolution device @code{latin1} This is similar to the high-resolution device except that the positioning is done at a minor scale. Some comments (lines starting with @samp{#}) were added for clarification; they were not generated by the formatter. @example @group shell> echo "hell world" | groff -Z -T latin1 # prologue x T latin1 x res 240 24 40 x init @end group # begin a new page p1 # font setup x font 1 R f1 s10 # initial positioning on the page V40 H0 # write text `hell' thell # inform about space, and issue a horizontal jump wh24 # write text `world' tworld # announce line break, but do nothing because ... n40 0 @group # ... the end of the document has been reached x trailer V2640 x stop @end group @end example @noindent This output can be fed into @code{grotty} to get a formatted text document. @item @acronym{AT&T} @code{troff} output Since a computer monitor has a very low resolution compared to modern printers the intermediate output for the X@tie{}Window devices can use the jump-and-write command with its 2-digit displacements. @example @group shell> echo "hell world" | groff -Z -T X100 x T X100 x res 100 1 1 x init @end group p1 x font 5 TR f5 s10 V16 H100 # write text with jump-and-write commands ch07e07l03lw06w11o07r05l03dh7 n16 0 @group x trailer V1100 x stop @end group @end example @noindent This output can be fed into @code{xditview} or @code{gxditview} for displaying in@tie{}X. Due to the obsolete jump-and-write command, the text clusters in the @acronym{AT&T} @code{troff} output are almost unreadable. @end table @c --------------------------------------------------------------------- @node Output Language Compatibility, , Intermediate Output Examples, gtroff Output @subsection Output Language Compatibility The intermediate output language of @acronym{AT&T} @code{troff} was first documented in the @acronym{UNIX} troff manual, with later additions documented in @cite{A Typesetter-indenpendent TROFF}, written by Brian Kernighan. The @code{gtroff} intermediate output format is compatible with this specification except for the following features. @itemize @bullet @item The classical quasi device independence is not yet implemented. @item The old hardware was very different from what we use today. So the @code{groff} devices are also fundamentally different from the ones in @acronym{AT&T} @code{troff}. For example, the @acronym{AT&T} PostScript device is called @code{post} and has a resolution of only 720 units per inch, suitable for printers 20 years ago, while @code{groff}'s @code{ps} device has a resolution of 72000 units per inch. Maybe, by implementing some rescaling mechanism similar to the classical quasi device independence, @code{groff} could emulate @acronym{AT&T}'s @code{post} device. @item The B-spline command @samp{D~} is correctly handled by the intermediate output parser, but the drawing routines aren't implemented in some of the postprocessor programs. @item The argument of the commands @samp{s} and @w{@samp{x H}} has the implicit unit scaled point @samp{z} in @code{gtroff}, while @acronym{AT&T} @code{troff} has point (@samp{p}). This isn't an incompatibility but a compatible extension, for both units coincide for all devices without a @code{sizescale} parameter in the @file{DESC} file, including all postprocessors from @acronym{AT&T} and @code{groff}'s text devices. The few @code{groff} devices with a @code{sizescale} parameter either do not exist for @acronym{AT&T} @code{troff}, have a different name, or seem to have a different resolution. So conflicts are very unlikely. @item The position changing after the commands @samp{Dp}, @samp{DP}, and @samp{Dt} is illogical, but as old versions of @code{gtroff} used this feature it is kept for compatibility reasons. @ignore Temporarily, there existed some confusion on the positioning after the @samp{D} commands that are groff extensions. This has been clarified by establishing the classical rule for all @code{groff} drawing commands: @itemize @item The position after a graphic object has been drawn is at its end; for circles and ellipses, the `end' is at the right side. @item From this, the positionings specified for the drawing commands above follow quite naturally. @end itemize @end ignore @end itemize @c ===================================================================== @node Font Files, , gtroff Output, File formats @section Font Files @cindex font files @cindex files, font The @code{gtroff} font format is roughly a superset of the @code{ditroff} font format (as used in later versions of @acronym{AT&T} @code{troff} and its descendants). Unlike the @code{ditroff} font format, there is no associated binary format; all files are text files.@footnote{Plan@tie{}9 @code{troff} has also abandoned the binary format.} The font files for device @var{name} are stored in a directory @file{dev@var{name}}. There are two types of file: a device description file called @file{DESC} and for each font@tie{}@var{f} a font file called@tie{}@file{@var{f}}. @menu * DESC File Format:: * Font File Format:: @end menu @c --------------------------------------------------------------------- @node DESC File Format, Font File Format, Font Files, Font Files @subsection @file{DESC} File Format @cindex @file{DESC} file, format @cindex font description file, format @cindex format of font description file @pindex DESC@r{ file format} The @file{DESC} file can contain the following types of line. Except for the @code{charset} keyword which must comes last (if at all), the order of the lines is not important. @table @code @item res @var{n} @kindex res @cindex device resolution @cindex resolution, device There are @var{n}@tie{}machine units per inch. @item hor @var{n} @kindex hor @cindex horizontal resolution @cindex resolution, horizontal The horizontal resolution is @var{n}@tie{}machine units. All horizontal quantities are rounded to be multiples of this value. @item vert @var{n} @kindex vert @cindex vertical resolution @cindex resolution, vertical The vertical resolution is @var{n}@tie{}machine units. All vertical quantities are rounded to be multiples of this value. @item sizescale @var{n} @kindex sizescale The scale factor for point sizes. By default this has a value of@tie{}1. One scaled point is equal to one point/@var{n}. The arguments to the @code{unitwidth} and @code{sizes} commands are given in scaled points. @xref{Fractional Type Sizes}, for more information. @item unitwidth @var{n} @kindex unitwidth Quantities in the font files are given in machine units for fonts whose point size is @var{n}@tie{}scaled points. @item prepro @var{program} @kindex prepro Call @var{program} as a preprocessor. Currently, this keyword is used by @code{groff} with option @option{-Thtml} only. @item postpro @var{program} @kindex postpro Call @var{program} as a postprocessor. For example, the line @Example postpro grodvi @endExample @noindent in the file @file{devdvi/DESC} makes @code{groff} call @code{grodvi} if option @option{-Tdvi} is given (and @option{-Z} isn't used). @item tcommand @kindex tcommand This means that the postprocessor can handle the @samp{t} and @samp{u} intermediate output commands. @item sizes @var{s1} @var{s2} @dots{} @var{sn} 0 @kindex sizes This means that the device has fonts at @var{s1}, @var{s2}, @dots{} @var{sn} scaled points. The list of sizes must be terminated by@tie{}0 (this is digit zero). Each @var{si} can also be a range of sizes @var{m}-@var{n}. The list can extend over more than one line. @item styles @var{S1} @var{S2} @dots{} @var{Sm} @kindex styles The first @var{m}@tie{}font positions are associated with styles @var{S1} @dots{} @var{Sm}. @item fonts @var{n} @var{F1} @var{F2} @var{F3} @dots{} @var{Fn} @kindex fonts Fonts @var{F1} @dots{} @var{Fn} are mounted in the font positions @var{m}+1, @dots{}, @var{m}+@var{n} where @var{m} is the number of styles. This command may extend over more than one line. A font name of@tie{}0 means no font is mounted on the corresponding font position. @item family @var{fam} @kindex family The default font family is @var{fam}. @item use_charnames_in_special @kindex use_charnames_in_special This command indicates that @code{gtroff} should encode special characters inside special commands. Currently, this is only used by the @acronym{HTML} output device. @xref{Postprocessor Access}. @item papersize @var{string} @dots{} @kindex papersize Select a paper size. Valid values for @var{string} are the ISO paper types @code{A0}-@code{A7}, @code{B0}-@code{B7}, @code{C0}-@code{C7}, @code{D0}-@code{D7}, @code{DL}, and the US paper types @code{letter}, @code{legal}, @code{tabloid}, @code{ledger}, @code{statement}, @code{executive}, @code{com10}, and @code{monarch}. Case is not significant for @var{string} if it holds predefined paper types. Alternatively, @var{string} can be a file name (e.g.@: @file{/etc/papersize}); if the file can be opened, @code{groff} reads the first line and tests for the above paper sizes. Finally, @var{string} can be a custom paper size in the format @code{@var{length},@var{width}} (no spaces before and after the comma). Both @var{length} and @var{width} must have a unit appended; valid values are @samp{i} for inches, @samp{C} for centimeters, @samp{p} for points, and @samp{P} for picas. Example: @code{12c,235p}. An argument which starts with a digit is always treated as a custom paper format. @code{papersize} sets both the vertical and horizontal dimension of the output medium. More than one argument can be specified; @code{groff} scans from left to right and uses the first valid paper specification. @item pass_filenames @kindex pass_filenames Tell @code{gtroff} to emit the name of the source file currently being processed. This is achieved by the intermediate output command @samp{F}. Currently, this is only used by the @acronym{HTML} output device. @item print @var{program} @kindex print Use @var{program} as a spooler program for printing. If omitted, the @option{-l} and @option{-L} options of @code{groff} are ignored. @item charset @kindex charset This line and everything following in the file are ignored. It is allowed for the sake of backwards compatibility. @end table The @code{res}, @code{unitwidth}, @code{fonts}, and @code{sizes} lines are mandatory. Other commands are ignored by @code{gtroff} but may be used by postprocessors to store arbitrary information about the device in the @file{DESC} file. @kindex spare1 @kindex spare2 @kindex biggestfont Here a list of obsolete keywords which are recognized by @code{groff} but completely ignored: @code{spare1}, @code{spare2}, @code{biggestfont}. @c --------------------------------------------------------------------- @node Font File Format, , DESC File Format, Font Files @subsection Font File Format @cindex font file, format @cindex font description file, format @cindex format of font files @cindex format of font description files A @dfn{font file}, also (and probably better) called a @dfn{font description file}, has two sections. The first section is a sequence of lines each containing a sequence of blank delimited words; the first word in the line is a key, and subsequent words give a value for that key. @table @code @item name @var{f} @kindex name The name of the font is@tie{}@var{f}. @item spacewidth @var{n} @kindex spacewidth The normal width of a space is@tie{}@var{n}. @item slant @var{n} @kindex slant The glyphs of the font have a slant of @var{n}@tie{}degrees. (Positive means forward.) @item ligatures @var{lig1} @var{lig2} @dots{} @var{lign} [0] @kindex ligatures Glyphs @var{lig1}, @var{lig2}, @dots{}, @var{lign} are ligatures; possible ligatures are @samp{ff}, @samp{fi}, @samp{fl}, @samp{ffi} and @samp{ffl}. For backwards compatibility, the list of ligatures may be terminated with a@tie{}0. The list of ligatures may not extend over more than one line. @item special @cindex special fonts @kindex special The font is @dfn{special}; this means that when a glyph is requested that is not present in the current font, it is searched for in any special fonts that are mounted. @end table Other commands are ignored by @code{gtroff} but may be used by postprocessors to store arbitrary information about the font in the font file. @cindex comments in font files @cindex font files, comments @kindex # The first section can contain comments which start with the @samp{#} character and extend to the end of a line. The second section contains one or two subsections. It must contain a @code{charset} subsection and it may also contain a @code{kernpairs} subsection. These subsections can appear in any order. Each subsection starts with a word on a line by itself. @kindex charset The word @code{charset} starts the character set subsection.@footnote{This keyword is misnamed since it starts a list of ordered glyphs, not characters.} The @code{charset} line is followed by a sequence of lines. Each line gives information for one glyph. A line comprises a number of fields separated by blanks or tabs. The format is @quotation @var{name} @var{metrics} @var{type} @var{code} [@var{entity-name}] [@code{--} @var{comment}] @end quotation @cindex 8-bit input @cindex input, 8-bit @cindex accessing unnamed glyphs with @code{\N} @cindex unnamed glyphs, accessing with @code{\N} @cindex characters, unnamed, accessing with @code{\N} @cindex glyphs, unnamed, accessing with @code{\N} @kindex --- @noindent @var{name} identifies the glyph name@footnote{The distinction between input, characters, and output, glyphs, is not clearly separated in the terminology of @code{groff}; for example, the @code{char} request should be called @code{glyph} since it defines an output entity.}: If @var{name} is a single character@tie{}@var{c} then it corresponds to the @code{gtroff} input character@tie{}@var{c}; if it is of the form @samp{\@var{c}} where @var{c} is a single character, then it corresponds to the special character @code{\[@var{c}]}; otherwise it corresponds to the special character @samp{\[@var{name}]}. If it is exactly two characters @var{xx} it can be entered as @samp{\(@var{xx}}. Note that single-letter special characters can't be accessed as @samp{\@var{c}}; the only exception is @samp{\-} which is identical to @code{\[-]}. @code{gtroff} supports 8-bit input characters; however some utilities have difficulties with eight-bit characters. For this reason, there is a convention that the entity name @samp{char@var{n}} is equivalent to the single input character whose code is@tie{}@var{n}. For example, @samp{char163} would be equivalent to the character with code@tie{}163 which is the pounds sterling sign in the ISO@tie{}@w{Latin-1} character set. You shouldn't use @samp{char@var{n}} entities in font description files since they are related to input, not output. Otherwise, you get hard-coded connections between input and output encoding which prevents use of different (input) character sets. The name @samp{---} is special and indicates that the glyph is unnamed; such glyphs can only be used by means of the @code{\N} escape sequence in @code{gtroff}. The @var{type} field gives the glyph type: @table @code @item 1 the glyph has a descender, for example, @samp{p}; @item 2 the glyph has an ascender, for example, @samp{b}; @item 3 the glyph has both an ascender and a descender, for example, @samp{(}. @end table The @var{code} field gives the code which the postprocessor uses to print the glyph. The glyph can also be input to @code{gtroff} using this code by means of the @code{\N} escape sequence. @var{code} can be any integer. If it starts with @samp{0} it is interpreted as octal; if it starts with @samp{0x} or @samp{0X} it is interpreted as hexadecimal. Note, however, that the @code{\N} escape sequence only accepts a decimal integer. The @var{entity-name} field gives an @acronym{ASCII} string identifying the glyph which the postprocessor uses to print the @code{gtroff} glyph @var{name}. This field is optional and has been introduced so that the @acronym{HTML} device driver can encode its character set. For example, the glyph @samp{\[Po]} is represented as @samp{£} in @acronym{HTML} 4.0. Anything on the line after the @var{entity-name} field resp.@: after @samp{--} will be ignored. The @var{metrics} field has the form: @display @group @var{width}[@code{,}@var{height}[@code{,}@var{depth}[@code{,}@var{italic-correction} [@code{,}@var{left-italic-correction}[@code{,}@var{subscript-correction}]]]]] @end group @end display @noindent There must not be any spaces between these subfields (it has been split here into two lines for better legibility only). Missing subfields are assumed to be@tie{}0. The subfields are all decimal integers. Since there is no associated binary format, these values are not required to fit into a variable of type @samp{char} as they are in @code{ditroff}. The @var{width} subfield gives the width of the glyph. The @var{height} subfield gives the height of the glyph (upwards is positive); if a glyph does not extend above the baseline, it should be given a zero height, rather than a negative height. The @var{depth} subfield gives the depth of the glyph, that is, the distance from the baseline to the lowest point below the baseline to which the glyph extends (downwards is positive); if a glyph does not extend below the baseline, it should be given a zero depth, rather than a negative depth. The @var{italic-correction} subfield gives the amount of space that should be added after the glyph when it is immediately to be followed by a glyph from a roman font. The @var{left-italic-correction} subfield gives the amount of space that should be added before the glyph when it is immediately to be preceded by a glyph from a roman font. The @var{subscript-correction} gives the amount of space that should be added after a glyph before adding a subscript. This should be less than the italic correction. A line in the @code{charset} section can also have the format @Example @var{name} " @endExample @noindent This indicates that @var{name} is just another name for the glyph mentioned in the preceding line. @kindex kernpairs The word @code{kernpairs} starts the kernpairs section. This contains a sequence of lines of the form: @Example @var{c1} @var{c2} @var{n} @endExample @noindent This means that when glyph @var{c1} appears next to glyph @var{c2} the space between them should be increased by@tie{}@var{n}. Most entries in the kernpairs section have a negative value for@tie{}@var{n}. @c ===================================================================== @c ===================================================================== @node Installation, Copying This Manual, File formats, Top @chapter Installation @cindex installation @c XXX @c ===================================================================== @c ===================================================================== @node Copying This Manual, Request Index, Installation, Top @appendix Copying This Manual @menu * GNU Free Documentation License:: License for copying this manual. @end menu @include fdl.texi @c ===================================================================== @c ===================================================================== @node Request Index, Escape Index, Copying This Manual, Top @appendix Request Index Requests appear without the leading control character (normally either @samp{.} or @samp{'}). @printindex rq @c ===================================================================== @c ===================================================================== @node Escape Index, Operator Index, Request Index, Top @appendix Escape Index Any escape sequence @code{\@var{X}} with @var{X} not in the list below emits a warning, printing glyph @var{X}. @printindex es @c ===================================================================== @c ===================================================================== @node Operator Index, Register Index, Escape Index, Top @appendix Operator Index @printindex op @c ===================================================================== @c ===================================================================== @node Register Index, Macro Index, Operator Index, Top @appendix Register Index The macro package or program a specific register belongs to is appended in brackets. A register name@tie{}@code{x} consisting of exactly one character can be accessed as @samp{\nx}. A register name @code{xx} consisting of exactly two characters can be accessed as @samp{\n(xx}. Register names @code{xxx} of any length can be accessed as @samp{\n[xxx]}. @printindex vr @c ===================================================================== @c ===================================================================== @node Macro Index, String Index, Register Index, Top @appendix Macro Index The macro package a specific macro belongs to is appended in brackets. They appear without the leading control character (normally @samp{.}). @printindex ma @c ===================================================================== @c ===================================================================== @node String Index, Glyph Name Index, Macro Index, Top @appendix String Index The macro package or program a specific string belongs to is appended in brackets. A string name@tie{}@code{x} consisting of exactly one character can be accessed as @samp{\*x}. A string name @code{xx} consisting of exactly two characters can be accessed as @samp{\*(xx}. String names @code{xxx} of any length can be accessed as @samp{\*[xxx]}. @printindex st @c ===================================================================== @c ===================================================================== @node Glyph Name Index, Font File Keyword Index, String Index, Top @appendix Glyph Name Index A glyph name @code{xx} consisting of exactly two characters can be accessed as @samp{\(xx}. Glyph names @code{xxx} of any length can be accessed as @samp{\[xxx]}. @c XXX @c ===================================================================== @c ===================================================================== @node Font File Keyword Index, Program and File Index, Glyph Name Index, Top @appendix Font File Keyword Index @printindex ky @c ===================================================================== @c ===================================================================== @node Program and File Index, Concept Index, Font File Keyword Index, Top @appendix Program and File Index @printindex pg @c ===================================================================== @c ===================================================================== @node Concept Index, , Program and File Index, Top @appendix Concept Index @printindex cp @bye