Sun Microsystems have released a Multi-Schema XML Validator, a Java tool for validating XML documents against a variety of XML schema languages.

The MSV tool supports RELAX NG, RELAX Namespace, RELAX Core, TREX, XML DTDs, and a subset of XML Schema Part 1.

MSV can either be used as a standalone command line program, or as a library to equip programs with XML validation capabilities. Source code and detailed documentation are included in the download.