\X Match eXtended Unicode "combining character sequence",
equivalent to C<(?:\PM\pM*)>
\C Match a single C char (octet) even under utf8.
- (Currently this does not work correctly.)
A C<\w> matches a single alphanumeric character or C<_>, not a whole word.
Use C<\w+> to match a string of Perl-identifier characters (which isn't