Well, yes, actually one of my modules follows this naming style. Win32::Daemon::Simple provides a simplified (yet at the same time extended) interface to Win32::Daemon. The thing is that HTML::?Filter doesn't use HTML::TagFilter. Then there's CGI::Simple that provides part of the CGI.pm functionality and thus the code of the module is simpler ... this is not the case either. HTML::?Filter is totally independent to HTML::TagFilter. I did not know about HTML::TagFilter (if it even was already on CPAN which I doubt) when writing HTML::?Filter.