@section @code{setenv}
@findex setenv
-POSIX specification: @url{http://www.opengroup.org/onlinepubs/9699919799/functions/setenv.html}
+POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/setenv.html}
Gnulib module: setenv
@itemize
@item
This function is missing on some platforms:
-AIX 4.3.2, HP-UX 11, IRIX 6.5, Solaris 9, mingw, BeOS.
+AIX 4.3.2, HP-UX 11.23, IRIX 6.5, Solaris 9, mingw, MSVC 9, BeOS.
+@item
+This function is not declared on some platforms:
+OSF/1 5.1.
+@item
+On some platforms, this function does not fail with @samp{EINVAL} when
+passed an empty string or a string containing @samp{=}:
+Mac OS X 10.5, FreeBSD 6.0, NetBSD 1.6, OpenBSD 3.8, Cygwin 1.5.x.
+@item
+On some platforms, this function removes a leading @samp{=} from the
+value argument:
+Cygwin 1.5.x.
@end itemize
Portability problems not fixed by Gnulib:
@itemize
@item
-In some versions of glibc (e.g.@: 2.3.3), @code{setenv} doesn't fail if the
-first argument contains a @samp{=} character.
+Older versions of POSIX required that @code{setenv(NULL,"",0)} gracefully
+fail with @code{EINVAL}, but not all implementations guarantee this,
+and the requirement was removed.
@end itemize