Following Jonathan Borden's announcement of a Schematron schema for RDDL, Rick Jelliffe has announced a RDDL description of Schematron and given some news on the 1.5 implementation.

The Schematron schema to RDDL is a new example of the flexibility of this language to express constraints that cannot easily be expressed using other schema languages:

Schematron is interesting in that it allows constraints which are otherwise very difficult to express in for example RELAX or TREX. For example, an xlink:arcrole and xlink:role must have a value of a URI reference, but not a relative URI reference. (This could also be expressed in an XML Schema pattern).

RDDL is now used by the Schematron home page, which has taken this opportunity to integrate more related resources:

• A new DTD for Schematron 1.5, upgraded to allow convenient namespace prefixing ("sch:") if desired.
• A new W3C XML Schema for Schematron 1.5.
• A new Schematron 1.5 Schema for Schematron 1.5
• An updated Schematron 1.5 spec, to be "submitted to W3C as a note after trimming".
• A quick reference page with a simplified DTD and full combined productions from the 4 W3C specs involved.

Jelliffe has also reported on Schematron 1.5 implementation status (should be available "early next week") and provided a tip on using Schematron as a XSLT debugger.