The Topic Map Constraint Language standard, which defines a way to create constraints/ schema for topic maps is moving into the final stages of the ISO process.
This standard is really comprised of two parts; the first is a generic framework to enable anyone to create custom constraints and have them evaluated as part of the TMCL evaluation model. The second part defines around 20 built in constraint types for the most common use cases.
TMCL uses the TMDM to store constraints and thus uses CTM as one authoring syntax.
We will be updating and publishing the TMCL tutorial that we have given several times now, both as a full document and as a series of blog entries.
The editors welcome all comments and feedback, the latest document can be found here