I posted this link about Thesaurus::RDF, The RDF Thesaurus descriptor standard under the OPML thread so thought I'd surface it here in case it gets missed.

This document describes an RDF implementation of a representation of terms of a thesaurus. The definition of a thesaurus follows that of the NISO specification z39.19. This specification is intended as a method for thesaurus servers to transfer all or part of a thesaurus to an application.