the IO handle, used for file handles (L<perlfunc/open>), sockets
(L<perlfunc/socket> and L<perlfunc/socketpair>), and directory
handles (L<perlfunc/opendir>). For compatibility with previous
-versions of Perl, C<*foo{FILEHANDLE}> is a synonym for C<*foo{IO}>.
+versions of Perl, C<*foo{FILEHANDLE}> is a synonym for C<*foo{IO}>, though it
+is deprecated as of 5.8.0. If deprecation warnings are in effect, it will warn
+of its use.
C<*foo{THING}> returns undef if that particular THING hasn't been used yet,
except in the case of scalars. C<*foo{SCALAR}> returns a reference to an