I have explored net, but without bingo. There are links, which may help, not assorted:
http://perl-xml.sourceforge.net/faq/
http://www.geocities.com/tlhome2000/form6/
http://ausweb.scu.edu.au/aw02/papers/refereed/fitch/paper.html
http://search.cpan.org/~jenda/XML-DTDParser-2.01/DTDParser.pm
http://search.cpan.org/~morni/XML-ParseDTD-0.1.4/ParseDTD.pm
http://xml.ascc.net/resource/schematron/
http://search.cpan.org/~abw/XML-Schema-0.07/lib/XML/Schema.pm