5 POSIX specification: @url{http://www.opengroup.org/susv3xsh/perror.html}
9 Portability problems fixed by Gnulib:
12 This function does not support the error values that are specified by POSIX
13 but not defined by the system, on some platforms:
14 OpenBSD 4.0, OSF/1 5.1, Cygwin, mingw.
17 Portability problems not fixed by Gnulib: