The Schematron XML validation language has been around for about as long as XML and has been used extensively for validation tasks outside the gamut of what XML Schema 1.0 was designed for. The reference implementation is implemented, with great care, in XSLT, and with extensibility in mind. There are a number of points in the Schematron compilation process that provide opportunities to extend its basic behavior and allow other modes of report output to be generated. This paper looks at one example of extending Schematron to create an XML to RDF Mapping Language for flexible RDF triple construction and built-in source-data validation rules.
Philip Fennell. "Schematron - More useful than you'd thought"
Presented at XML London 2014, June 7-8th, 2014.