It would be nice to forbid labels with keyword names, to avoid confusion.
+=head2 truncate() prototype
+
+The prototype of truncate() is currently C<$$>. It should probably
+be C<*$> instead. (This is changed in F<opcode.pl>)
+
=head2 error reporting of [$a ; $b]
Using C<;> inside brackets is a syntax error, and we don't propose to change