Jonathan Borden, stalwart of the RDDL effort, has created a new experimental language, TDDL (Terminology Definition Description Language), an XHTML based version of RDF Schema.

Incorporating RDF Schema functionality, TDDL is designed to serve as a way to define terminologies in a way that is both human and machine readable. Borden writes about TDDL's creation:

This is an experiment, designed to highlight issues in describing terminologies. I created TDDL during the process of developing RDDL simply as an experiment and have not published these URLs. This topic came up for discussion today on the RDFIG IRC channel and so I am publishing these URLs for further discussion. TDDL was particularly inspired by DanC's HyperRDF.

For an example, see the TDDL definition of TDDL itself. As Borden notes, his TDDL work is not part of the RDDL specification, and is purely experimental.

(Suggestions to xmlhack for witty "TDDL" puns gladly accepted.)