The upstream author is: 

Ken Williams <ken@mathforum.org>, based extremely heavily on
collaborative work with Dave Rolsky <autarch@urth.org> and Jonathan
Swartz <swartz@pobox.com> on the HTML::Mason project..

This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

Larry Wall's "Artistic License" for perl can be found in
/usr/share/common-licenses/Artistic, and the GPL can be found in
/usr/share/common-licenses/GPL-2.