-If you are upgrading from an earlier release such as 5.23.2, first read
-L<perl5233delta>, which describes differences between 5.23.2 and 5.23.3.
-
-=head1 Incompatible Changes
-
-=head2 Lexical $_ has been removed
-
-C<my $_> was introduced in Perl 5.10, and subsequently caused much confusion
-with no obvious solution. In Perl 5.18.0, it was made experimental on the
-theory that it would either be removed or redesigned in a less confusing (but
-backward-incompatible) way. Over the following years, no alternatives were
-proposed. The feature has now been removed and will fail to compile.
-
-=head2 Only blanks and tabs are now allowed within C<[...]> within C<(?[...])>.
-
-The experimental Extended Bracketed Character Classes can contain regular
-bracketed character classes within them. These differ from regular ones in
-that white space is generally ignored, unless escaped by preceding it with a
-backslash. The white space that is ignored is now limited to just tab C<\t>
-and SPACE characters. Previously, it was any white space. See
-L<perlrecharclass/Extended Bracketed Character Classes>.
-
-=head1 Performance Enhancements
+If you are upgrading from an earlier release such as 5.23.5, first read
+L<perl5236delta>, which describes differences between 5.23.5 and 5.23.6.