POSIX specification: http://www.opengroup.org/susv3xbd/errno.h.html
Gnulib module: errno
Portability problems fixed by Gnulib:
EOVERFLOW, ENOLINK, EMULTIHOP are not defined
on some platforms:
OpenBSD 4.0, OSF/1 5.1, mingw.
ECANCELED is not defined on some platforms:
OpenBSD 4.0, Cygwin, mingw.
ENOMSG, EIDRM, EPROTO, EBADMSG,
ENOTSUP are not defined on some platforms:
OpenBSD 4.0, mingw.
EWOULDBLOCK, ETXTBSY, ELOOP, ENOTSOCK,
EDESTADDRREQ, EMSGSIZE, EPROTOTYPE, ENOPROTOOPT,
EPROTONOSUPPORT, EOPNOTSUPP, EAFNOSUPPORT,
EADDRINUSE, EADDRNOTAVAIL, ENETDOWN, ENETUNREACH,
ENETRESET, ECONNABORTED, ECONNRESET, ENOBUFS,
EISCONN, ENOTCONN, ETIMEDOUT, ECONNREFUSED,
EHOSTUNREACH, EALREADY, EINPROGRESS, ESTALE,
EDQUOT are not defined on some platforms:
mingw.
Portability problems not fixed by Gnulib: