+@item
+The @code{getopt} function keeps some internal state that cannot be explicitly
+reset on some platforms:
+mingw.
+@item
+The value of @code{optind} after a missing required argument is wrong
+on some platforms:
+MacOS 10.5, AIX 7.1.
+@end itemize
+
+Portability problems fixed by Gnulib module @code{getopt-gnu}:
+@itemize
+@item
+The function @code{getopt} does not support the @samp{+} flag in the options
+string on some platforms:
+MacOS X 10.5, AIX 5.2, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 11 2010-11.
+@item
+The function @code{getopt} does not obey the combination of @samp{+}
+and @samp{:} flags in the options string on some platforms:
+glibc 2.11.
+@item
+The function @code{getopt} does not obey the @samp{-} flag in the options
+string when @env{POSIXLY_CORRECT} is set on some platforms:
+Cygwin 1.7.0.
+@item
+The function @code{getopt} does not support options with optional arguments
+on some platforms:
+MacOS X 10.5, OpenBSD 4.0, AIX 5.2, HP-UX 11, IRIX 6.5, OSF/1 5.1,
+Solaris 11 2010-11, Cygwin 1.5.x.
+@item
+The function @code{getopt_long} is missing on some platforms:
+AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 9, Interix 3.5.
+@item
+The function @code{getopt_long_only} is missing on some platforms:
+MacOS X 10.3, FreeBSD 5.2.1, NetBSD 5.0, AIX 5.1, HP-UX 11, IRIX 6.5,
+OSF/1 5.1, Solaris 9, mingw, Interix 3.5.