Thanks to Robin Cover, I have set up the OASIS-managed DITA RNG Converter GitHub project:
https://github.com/oasis-open/dita-rng-converter As outlined in the development plan, I will be working as soon as possible to make the code ready for general use, hopefully by the end of April. Cheers, E. ---- Eliot Kimber, Owner Contrext, LLC
http://contrext.com