The remaining locale category, C<LC_MESSAGES> (possibly supplemented
by others in particular implementations) is not currently used by
-Perl--except possibly to affect the behavior of library functions called
-by extensions outside the standard Perl distribution.
+Perl--except possibly to affect the behavior of library functions
+called by extensions outside the standard Perl distribution and by the
+operating system and its utilities. Note especially that the string
+value of C<$!> and the error messages given by external utilities may
+be changed by C<LC_MESSAGES>. If you want to have portable error
+codes, use C<%!>. See L<Errno>.
=head1 SECURITY
B<NOTE>: C<LANGUAGE> is a GNU extension, it affects you only if you
are using the GNU libc. This is the case if you are using e.g. Linux.
If you are using "commercial" UNIXes you are most probably I<not>
-using libc and you can ignore C<LANGUAGE>. But in the case you are
-using it: it is an even more powerful "override-all" than C<LC_ALL>
-and moreover, it's a "path" (":"-separated list) of locales.
+using GNU libc and you can ignore C<LANGUAGE>.
+
+However, in the case you are using C<LANGUAGE>: it affects the
+language of informational, warning, and error messages output by
+commands (in other words, it's like C<LC_MESSAGES>) but it has higher
+priority than L<LC_ALL>. Moreover, it's not a single value but
+instead a "path" (":"-separated list) of I<languages> (not locales).
+See the GNU C<gettext> library documentation for more information.
=item LC_CTYPE