xs3p was originally developed by DSTC and was availabe
through their website at http://titanium.dstc.edu.au/xml/xs3p/

Since the demise of this organization, we at FiForms Solutions
have decided to host xs3p, since we have been using it in
documenting the XML used in FiForms. The stylesheet has been
modified to point to the new xs3p home here at FiForms, while
still retaining the old (dead) link to the dstc website. The
xs3p home is http://xml.fiforms.org/xs3p/