+The constants @code{ERA}, @code{ERA_D_FMT}, @code{ERA_D_T_FMT},
+@code{ERA_T_FMT}, @code{ALT_DIGITS} are not supported on some platforms:
+OpenBSD 3.8.
+@end itemize
+
+Portability problems not fixed by Gnulib:
+@itemize
+@item
+On Cygwin 1.5.x, which doesn't have locales, @code{nl_langinfo(CODESET)} always