4 POSIX specification: @url{http://www.opengroup.org/susv3xbd/ftw.h.html}
8 Portability problems fixed by Gnulib:
12 Portability problems not fixed by Gnulib:
15 This header file is missing on some platforms:
16 MacOS X 10.3, FreeBSD 5.2.1, NetBSD 3.0, mingw, BeOS.