This convention is used in manpages for other UN*X systems to refer to
system values (availiable via sysconf() or pathconf()) rather than
definitions in <limits.h>.
Use .Fn rather than .Nm macro in HISTORY and STANDARDS sections.
Use .At and .St macros instead of spelling out "Version 6 UNIX",
"IEEE 1003.1-1988 (POSIX)", etc.