Sun multi-schema XML validator

 The Sun Multi-Schema XML Validator is a Java tool to validate XML
 documents against several kinds of XML schemata. It supports DTD,
 RELAX Namespace, RELAX Core, RELAX NG, TREX, and a subset of W3C
 XML Schema Part 1.
 .
 It features both a command line utility that can read XML documents and
 validate them against a schema and a library that can be incorporated in
 a Java program.