@item
This function does not support the error values that are specified by POSIX
but not defined by the system, on some platforms:
-OpenBSD 4.0, OSF/1 5.1, Cygwin 1.5.x, mingw.
+OpenBSD 4.0, OSF/1 5.1, Cygwin 1.5.x, mingw, MSVC 9.
+@item
+This function treats @code{errno} of 0 like failure, although POSIX
+requires that the message declare it as a success, on some platforms:
+FreeBSD 8.2, OpenBSD 4.7, MacOS X 10.5.
+@item
+This function clobbers the @code{strerror} buffer on some platforms:
+Cygwin 1.7.9.
+@item
+This function fails to print a useful a string for out-of-range integers on
+some platforms:
+HP-UX 11, IRIX 6.5, Solaris 8.
@end itemize
Portability problems not fixed by Gnulib:
@itemize
+@item
+POSIX requires that this function set the stream error bit (detected
+by @code{ferror}) on write failure, but not all platforms do this:
+glibc 2.13, cygwin 1.7.9.
+@item
+POSIX requires that this function not alter stream orientation, but
+the gnulib replacement locks in byte orientation and fails on wide
+character streams.
@end itemize