Ongoing work: DSDL and beyond

ISO Committee While RELAX NG came from OASIS and Schematron from an independent group, the DSDL work seeks to unify these specs under the more formal ISO umbrella.
Combines RELAX NG, Schematron, a framework for integrating schema languages, datatypes, character repertoire validation, and possible datatype and namespace-aware DTDs under one project.
Moving slowly RELAX NG is in the ISO approval process already, following on its predecessor, RELAX, which is already an ISO technical report. Some parts of the spec are more developed than others.
More information http://dsdl.org