POSIX specification: @url{http://www.opengroup.org/susv3xbd/stddef.h.html}
-Gnulib module: ---
+Gnulib module: stddef
Portability problems fixed by Gnulib:
@itemize
+@item
+Some old platforms fail to provide @code{wchar_t}.
+
+@item
+Some platforms provide a @code{NULL} macro that cannot be used in arbitrary
+expressions:
+NetBSD 5.0
@end itemize
Portability problems not fixed by Gnulib: