Jing is a RELAX NG validator written in Java. It implements the RELAX
NG 1.0 Specification, RELAX NG Compact Syntax, and parts of RELAX NG
DTD Compatibility, specifically checking of ID/IDREF/IDREFS. It also
has experimental support for schema languages other than RELAX NG;
specifically W3C XML Schema, Schematron 1.5, and Namespace Routing
Language.