+=head2 C<"$!"> text will be returned in UTF-8 when appropriate
+
+The stringification of C<$!> and C<$^E> will have the UTF-8 flag set
+when the text is actually non-ASCII UTF-8. This will enable programs
+that are set up to be locale-aware to properly output messages in the
+user's native language. Code that needs to continue the 5.20 and
+earlier behavior can do the stringification within the scopes of both
+'use bytes' and 'use locale ":messages". No other Perl operations will
+be affected by locale; only C<$!> and C<$^E> stringification. The
+'bytes' pragma causes the UTF-8 flag to not be set, just as in previous
+Perl releases. This resolves [perl #112208].
+
+=head2 MAD build option has been removed
+
+MAD = Misc Attribute Decoration; unmaintained attempt at preserving
+the Perl parse tree more faithfully so that automatic conversion of
+Perl 5 to Perl 6 would have been easier.
+
+This build-time configuration option had been unmaintained for years,
+and had probably seriously diverged on both Perl 5 and Perl 6 sides.
+
+=head2 Support for C<?PATTERN?> without explicit operator has been removed
+
+Starting regular expressions matching only once directly with the
+question mark delimiter is now a syntax error, so that the question mark
+can be available for use in new operators. Write C<m?PATTERN?> instead,
+explicitly using the C<m> operator: the question mark delimiter still
+invokes match-once behaviour.
+