C<__WARN__> hooks, as described in L<perlvar> and L<perlfunc/warn>.
See also L<perldiag> and L<perltrap>. A new, fine-grained warning
facility is also available if you want to manipulate entire classes
-of warnings; see L<warnings> (or better yet, its source code) about
-that.
+of warnings; see L<warnings> or L<perllexwarn>.
=item B<-W>