Status on Simplified docbook?

Hello!

Just a quick question. Currently, the Docbook subset Simplified Docbook is based on Docbook V4.3 (according to the documentation at OASIS) . Any plans to update to Docbook 5 in the near future? Besides that, I was not able to find any Relax-NG schema for Simplified Docbook, only DTD. I read somewhere that Relax NG schema for Docbook should be considered as normative. Are there any Relax NG schema files for Simplified Docbook for download somewhere?

Thank you.
/frank