4 POSIX specification: @url{http://www.opengroup.org/susv3xbd/fenv.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 FreeBSD 5.2.1, NetBSD 3.0, OpenBSD 3.8, AIX 5.1, IRIX 6.5, OSF/1 5.1, Cygwin,