fltk/documentation/license.dox

/**

 \page	license	J - Software License

<P ALIGN="RIGHT">December 11, 2001</P>

<P>The FLTK library and included programs are provided under the terms
of the GNU Library General Public License (LGPL) with the following
exceptions:</P>

<OL>

	<LI>Modifications to the FLTK configure script, config
	header file, and makefiles by themselves to support
	a specific platform do not constitute a modified or
	derivative work.<BR>
	<BR>
	The authors do request that such modifications be
	contributed to the FLTK project - send all
	contributions to "fltk-bugs@fltk.org".<BR>
	<BR>
	</LI>

	<LI>Widgets that are subclassed from FLTK widgets do not
	constitute a derivative work.<BR>
	<BR>
	</LI>

	<LI>Static linking of applications and widgets to the
	FLTK library does not constitute a derivative work
	and does not require the author to provide source
	code for the application or widget, use the shared
	FLTK libraries, or link their applications or
	widgets against a user-supplied version of FLTK.<BR>
	<BR>
	If you link the application or widget to a modified
	version of FLTK, then the changes to FLTK must be
	provided under the terms of the LGPL in sections
	1, 2, and 4.<BR>
	<BR>
	</LI>

	<LI>You do not have to provide a copy of the FLTK license
	with programs that are linked to the FLTK library, nor
	do you have to identify the FLTK license in your
	program or documentation as required by section 6
	of the LGPL.<BR>
	<BR>
	However, programs must still identify their use of FLTK.
	The following example statement can be included in user
	documentation to satisfy this requirement:<BR>
	<BR>
	<I>[program/widget] is based in part on the work of
	the FLTK project (http://www.fltk.org).</I></LI>

</OL>

<HR>

<P ALIGN=CENTER><B>GNU LIBRARY GENERAL PUBLIC LICENSE</B></P>
<P ALIGN=CENTER>Version 2, June 1991
<BR> Copyright (C) 1991 Free Software Foundation, Inc.
<BR> 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA
<BR> Everyone is permitted to copy and distribute verbatim copies of
this license document, but changing it is not allowed.
<BR> [This is the first released version of the library GPL.  It is
numbered 2 because it goes with version 2 of the ordinary GPL.] </P>
<P><B>Preamble</B></P>
 The licenses for most software are designed to take away your freedom
to share and change it.  By contrast, the GNU General Public Licenses
are intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users.
<P>This license, the Library General Public License, applies to some
specially designated Free Software Foundation software, and to any
other libraries whose authors decide to use it.  You can use it for
your libraries, too. </P>
<P>When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it in
new free programs; and that you know you can do these things. </P>
<P>To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the library, or if you modify it. </P>
<P>For example, if you distribute copies of the library, whether gratis
or for a fee, you must give the recipients all the rights that we gave
you.  You must make sure that they, too, receive or can get the source
code.  If you link a program with the library, you must provide
complete object files to the recipients so that they can relink them
with the library, after making changes to the library and recompiling
it.  And you must show them these terms so they know their rights. </P>
<P>Our method of protecting your rights has two steps: (1) copyright
the library, and (2) offer you this license which gives you legal
permission to copy, distribute and/or modify the library. </P>
<P>Also, for each distributor's protection, we want to make certain
that everyone understands that there is no warranty for this free
library.  If the library is modified by someone else and passed on, we
want its recipients to know that what they have is not the original
version, so that any problems introduced by others will not reflect on
the original authors' reputations. </P>
<P>Finally, any free program is threatened constantly by software
patents.  We wish to avoid the danger that companies distributing free
software will individually obtain patent licenses, thus in effect
transforming the program into proprietary software.  To prevent this,
we have made it clear that any patent must be licensed for everyone's
free use or not licensed at all. </P>
<P>Most GNU software, including some libraries, is covered by the
ordinary GNU General Public License, which was designed for utility
programs.  This license, the GNU Library General Public License,
applies to certain designated libraries.  This license is quite
different from the ordinary one; be sure to read it in full, and don't
assume that anything in it is the same as in the ordinary license. </P>
<P>The reason we have a separate public license for some libraries is
that they blur the distinction we usually make between modifying or
adding to a program and simply using it.  Linking a program with a
library, without changing the library, is in some sense simply using
the library, and is analogous to running a utility program or
application program.  However, in a textual and legal sense, the linked
executable is a combined work, a derivative of the original library,
and the ordinary General Public License treats it as such. </P>
<P>Because of this blurred distinction, using the ordinary General
Public License for libraries did not effectively promote software
sharing, because most developers did not use the libraries.  We
concluded that weaker conditions might promote sharing better. </P>
<P>However, unrestricted linking of non-free programs would deprive the
users of those programs of all benefit from the free status of the
libraries themselves.  This Library General Public License is intended
to permit developers of non-free programs to use free libraries, while
preserving your freedom as a user of such programs to change the free
libraries that are incorporated in them.  (We have not seen how to
achieve this as regards changes in header files, but we have achieved
it as regards changes in the actual functions of the Library.)  The
hope is that this will lead to faster development of free libraries. </P>
<P>The precise terms and conditions for copying, distribution and
modification follow.  Pay close attention to the difference between a
&quot;work based on the libary&quot; and a &quot;work that uses the library&quot;.  The
former contains code derived from the library, while the latter only
works together with the library. </P>
<P>Note that it is possible for a library to be covered by the ordinary
General Public License rather than by this special one. </P>
<P ALIGN="CENTER"><B>TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND
MODIFICATION</B></P>
<STRONG>0.</STRONG> This License Agreement applies to any software
library which contains a notice placed by the copyright holder or other
authorized party saying it may be distributed under the terms of this
Library General Public License (also called &quot;this License&quot;).  Each
licensee is addressed as &quot;you&quot;.
<P>A &quot;library&quot; means a collection of software functions and/or data
prepared so as to be conveniently linked with application programs
(which use some of those functions and data) to form executables. </P>
<P>The &quot;Library&quot;, below, refers to any such software library or work
which has been distributed under these terms.  A &quot;work based on the
Library&quot; means either the Library or any derivative work under
copyright law: that is to say, a work containing the Library or a
portion of it, either verbatim or with modifications and/or translated
straightforwardly into another language.  (Hereinafter, translation is
included without limitation in the term &quot;modification&quot;.) </P>
<P>&quot;Source code&quot; for a work means the preferred form of the work for
making modifications to it.  For a library, complete source code means
all the source code for all modules it contains, plus any associated
interface definition files, plus the scripts used to control
compilation and installation of the library. </P>
<P>Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope.  The act of
running a program using the Library is not restricted, and output from
such a program is covered only if its contents constitute a work based
on the Library (independent of the use of the Library in a tool for
writing it).  Whether that is true depends on what the Library does and
what the program that uses the Library does. </P>
<P><STRONG>1.</STRONG> You may copy and distribute verbatim copies of
the Library's complete source code as you receive it, in any medium,
provided that you conspicuously and appropriately publish on each copy
an appropriate copyright notice and disclaimer of warranty; keep intact
all the notices that refer to this License and to the absence of any
warranty; and distribute a copy of this License along with the Library. </P>
<P>You may charge a fee for the physical act of transferring a copy,
and you may at your option offer warranty protection in exchange for a
fee. </P>
<P><STRONG>2.</STRONG> You may modify your copy or copies of the
Library or any portion of it, thus forming a work based on the Library,
and copy and distribute such modifications or work under the terms of
Section 1 above, provided that you also meet all of these conditions:
<STRONG>a)</STRONG> The modified work must itself be a software
library.
<P><STRONG>b)</STRONG> You must cause the files modified to carry
prominent notices stating that you changed the files and the date of
any change. </P>
<P><STRONG>c)</STRONG> You must cause the whole of the work to be
licensed at no charge to all third parties under the terms of this
License. </P>
<P><STRONG>d)</STRONG> If a facility in the modified Library refers to
a function or a table of data to be supplied by an application program
that uses the facility, other than as an argument passed when the
facility is invoked, then you must make a good faith effort to ensure
that, in the event an application does not supply such function or
table, the facility still operates, and performs whatever part of its
purpose remains meaningful. </P>
<P>(For example, a function in a library to compute square roots has a
purpose that is entirely well-defined independent of the application.
 Therefore, Subsection 2d requires that any application-supplied
function or table used by this function must be optional: if the
application does not supply it, the square root function must still
compute square roots.) </P>

<P>These requirements apply to the modified work as a whole.
If identifiable sections of that work are not derived from the
Library, and can be reasonably considered independent and separate
works in themselves, then this License, and its terms, do not apply to
those sections when you distribute them as separate works.  But when
you distribute the same sections as part of a whole which is a work
based on the Library, the distribution of the whole must be on the
terms of this License, whose permissions for other licensees extend to
the entire whole, and thus to each and every part regardless of who
wrote it. </P>
<P>Thus, it is not the intent of this section to claim rights or
contest your rights to work written entirely by you; rather, the intent
is to exercise the right to control the distribution of derivative or
collective works based on the Library. </P>
<P>In addition, mere aggregation of another work not based on the
Library with the Library (or with a work based on the Library) on a
volume of a storage or distribution medium does not bring the other
work under the scope of this License. </P>
<P><STRONG>3.</STRONG> You may opt to apply the terms of the ordinary
GNU General Public License instead of this License to a given copy of
the Library.  To do this, you must alter all the notices that refer to
this License, so that they refer to the ordinary GNU General Public
License, version 2, instead of to this License.  (If a newer version
than version 2 of the ordinary GNU General Public License has appeared,
then you can specify that version instead if you wish.)  Do not make
any other change in these notices. </P>
<P>Once this change is made in a given copy, it is irreversible for
that copy, so the ordinary GNU General Public License applies to all
subsequent copies and derivative works made from that copy. </P>
<P>This option is useful when you wish to copy part of the code of the
Library into a program that is not a library. </P>
<P><STRONG>4.</STRONG> You may copy and distribute the Library (or a
portion or derivative of it, under Section 2) in object code or
executable form under the terms of Sections 1 and 2 above provided that
you accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections 1
and 2 above on a medium customarily used for software interchange. </P>
<P>If distribution of object code is made by offering access to copy
from a designated place, then offering equivalent access to copy the
source code from the same place satisfies the requirement to distribute
the source code, even though third parties are not compelled to copy
the source along with the object code. </P>
<P><STRONG>5.</STRONG> A program that contains no derivative of any
portion of the Library, but is designed to work with the Library by
being compiled or linked with it, is called a &quot;work that uses the
Library&quot;.  Such a work, in isolation, is not a derivative work of the
Library, and therefore falls outside the scope of this License. </P>
<P>However, linking a &quot;work that uses the Library&quot; with the Library
creates an executable that is a derivative of the Library (because it
contains portions of the Library), rather than a &quot;work that uses the
library&quot;.  The executable is therefore covered by this License. Section
6 states terms for distribution of such executables. </P>
<P>When a &quot;work that uses the Library&quot; uses material from a header file
that is part of the Library, the object code for the work may be a
derivative work of the Library even though the source code is not.
Whether this is true is especially significant if the work can be
linked without the Library, or if the work is itself a library.  The
threshold for this to be true is not precisely defined by law. </P>
<P>If such an object file uses only numerical parameters, data
structure layouts and accessors, and small macros and small inline
functions (ten lines or less in length), then the use of the object
file is unrestricted, regardless of whether it is legally a derivative
work.  (Executables containing this object code plus portions of the
Library will still fall under Section 6.) </P>
<P>Otherwise, if the work is a derivative of the Library, you may
distribute the object code for the work under the terms of Section 6.
Any executables containing that work also fall under Section 6, whether
or not they are linked directly with the Library itself. </P>
<P><STRONG>6.</STRONG> As an exception to the Sections above, you may
also compile or link a &quot;work that uses the Library&quot; with the Library to
produce a work containing portions of the Library, and distribute that
work under terms of your choice, provided that the terms permit
modification of the work for the customer's own use and reverse
engineering for debugging such modifications. </P>
<P>You must give prominent notice with each copy of the work that the
Library is used in it and that the Library and its use are covered by
this License.  You must supply a copy of this License.  If the work
during execution displays copyright notices, you must include the
copyright notice for the Library among them, as well as a reference
directing the user to the copy of this License.  Also, you must do one
of these things: <STRONG>a)</STRONG> Accompany the work
with the complete corresponding  machine-readable source code for the
Library including whatever  changes were used in the work (which must
be distributed under  Sections 1 and 2 above); and, if the work is an
executable linked  with the Library, with the complete machine-readable
&quot;work that  uses the Library&quot;, as object code and/or source code, so
that the  user can modify the Library and then relink to produce a
modified  executable containing the modified Library.  (It is
understood  that the user who changes the contents of definitions files
in the  Library will not necessarily be able to recompile the
application  to use the modified definitions.)
<P><STRONG>b)</STRONG> Accompany the work with a written offer, valid
for at  least three years, to give the same user the materials
 specified in Subsection 6a, above, for a charge no more  than the cost
of performing this distribution. </P>
<P><STRONG>c)</STRONG> If distribution of the work is made by offering
access to copy  from a designated place, offer equivalent access to
copy the above  specified materials from the same place. </P>
<P><STRONG>d)</STRONG> Verify that the user has already received a copy
of these  materials or that you have already sent this user a copy. </P>

<P>For an executable, the required form of the &quot;work that
uses the Library&quot; must include any data and utility programs needed for
reproducing the executable from it.  However, as a special exception,
the source code distributed need not include anything that is normally
distributed (in either source or binary form) with the major components
(compiler, kernel, and so on) of the operating system on which the
executable runs, unless that component itself accompanies the
executable.</P>
<P>It may happen that this requirement contradicts the license
restrictions of other proprietary libraries that do not normally
accompany the operating system.  Such a contradiction means you cannot
use both them and the Library together in an executable that you
distribute. </P>
<P><STRONG>7.</STRONG> You may place library facilities that are a work
based on the Library side-by-side in a single library together with
other library facilities not covered by this License, and distribute
such a combined library, provided that the separate distribution of the
work based on the Library and of the other library facilities is
otherwise permitted, and provided that you do these two things:
<STRONG>a)</STRONG> Accompany the combined library with a copy of the
same work  based on the Library, uncombined with any other library
 facilities.  This must be distributed under the terms of the  Sections
above.
<P><STRONG>b)</STRONG> Give prominent notice with the combined library
of the fact that part of it is a work based on the Library, and
explaining where to find the accompanying uncombined form of the same
work. </P>

<P><STRONG>8.</STRONG> You may not copy, modify, sublicense,
link with, or distribute the Library except as expressly provided under
this License.  Any attempt otherwise to copy, modify, sublicense, link
with, or distribute the Library is void, and will automatically
terminate your rights under this License.  However, parties who have
received copies, or rights, from you under this License will not have
their licenses terminated so long as such parties remain in full
compliance. </P>
<P><STRONG>9.</STRONG> You are not required to accept this License,
since you have not signed it.  However, nothing else grants you
permission to modify or distribute the Library or its derivative works.
 These actions are prohibited by law if you do not accept this License.
 Therefore, by modifying or distributing the Library (or any work based
on the Library), you indicate your acceptance of this License to do so,
and all its terms and conditions for copying, distributing or modifying
the Library or works based on it. </P>
<P><STRONG>10.</STRONG> Each time you redistribute the Library (or any
work based on the Library), the recipient automatically receives a
license from the original licensor to copy, distribute, link with or
modify the Library subject to these terms and conditions.  You may not
impose any further restrictions on the recipients' exercise of the
rights granted herein. You are not responsible for enforcing compliance
by third parties to this License. </P>
<P><STRONG>11.</STRONG> If, as a consequence of a court judgment or
allegation of patent infringement or for any other reason (not limited
to patent issues), conditions are imposed on you (whether by court
order, agreement or otherwise) that contradict the conditions of this
License, they do not excuse you from the conditions of this License.
 If you cannot distribute so as to satisfy simultaneously your
obligations under this License and any other pertinent obligations,
then as a consequence you may not distribute the Library at all.  For
example, if a patent license would not permit royalty-free
redistribution of the Library by all those who receive copies directly
or indirectly through you, then the only way you could satisfy both it
and this License would be to refrain entirely from distribution of the
Library. </P>
<P>If any portion of this section is held invalid or unenforceable
under any particular circumstance, the balance of the section is
intended to apply, and the section as a whole is intended to apply in
other circumstances. </P>
<P>It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system which is implemented
by public license practices.  Many people have made generous
contributions to the wide range of software distributed through that
system in reliance on consistent application of that system; it is up
to the author/donor to decide if he or she is willing to distribute
software through any other system and a licensee cannot impose that
choice. </P>
<P>This section is intended to make thoroughly clear what is believed
to be a consequence of the rest of this License. </P>
<P><STRONG>12.</STRONG> If the distribution and/or use of the Library
is restricted in certain countries either by patents or by copyrighted
interfaces, the original copyright holder who places the Library under
this License may add an explicit geographical distribution limitation
excluding those countries, so that distribution is permitted only in or
among countries not thus excluded.  In such case, this License
incorporates the limitation as if written in the body of this License. </P>
<P><STRONG>13.</STRONG> The Free Software Foundation may publish
revised and/or new versions of the Library General Public License from
time to time. Such new versions will be similar in spirit to the
present version, but may differ in detail to address new problems or
concerns. </P>
<P>Each version is given a distinguishing version number.  If the
Library specifies a version number of this License which applies to it
and &quot;any later version&quot;, you have the option of following the terms and
conditions either of that version or of any later version published by
the Free Software Foundation.  If the Library does not specify a
license version number, you may choose any version ever published by
the Free Software Foundation. </P>
<P><STRONG>14.</STRONG> If you wish to incorporate parts of the Library
into other free programs whose distribution conditions are incompatible
with these, write to the author to ask for permission.  For software
which is copyrighted by the Free Software Foundation, write to the Free
Software Foundation; we sometimes make exceptions for this.  Our
decision will be guided by the two goals of preserving the free status
of all derivatives of our free software and of promoting the sharing
and reuse of software generally. </P>
<P ALIGN="CENTER"><B>NO WARRANTY</B></P>
<P><STRONG>15.</STRONG> BECAUSE THE LIBRARY IS LICENSED FREE OF CHARGE,
THERE IS NO WARRANTY FOR THE LIBRARY, TO THE EXTENT PERMITTED BY
APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE LIBRARY &quot;AS IS&quot; WITHOUT
WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE
OF THE LIBRARY IS WITH YOU.  SHOULD THE LIBRARY PROVE DEFECTIVE, YOU
ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. </P>
<P><STRONG>16.</STRONG> IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW
OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY
WHO MAY MODIFY AND/OR REDISTRIBUTE THE LIBRARY AS PERMITTED ABOVE, BE
LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL
OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
LIBRARY (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
FAILURE OF THE LIBRARY TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES. </P>
<P ALIGN="CENTER"><B>END OF TERMS AND CONDITIONS</B></P>

*/