This draft was written to support OCCI's needs and extensions are certainly something we can put to good use. You can be sure that all renderings will support both link and category constructs too. For the XML rendering, in order to support both user (browser) and machine (software) clients we decided to go with XHTML which we'll focus on once we've digested the public feedback and filled in the gaps in the existing specification. It's not too late for you to provide input so if you have any feedback then it would be gratefully received.

Cheers,

Sam