In Memphis and at WWW6, a number of us talked about synchronising the negotiation metadata models for PEP, transparent content negotiation, and possibly user-agent side rendering scripts. What came out was that transparent content negotiation would place its feature tags in the URI namespace, like PEP does for its extension identifiers. This eases metadata aministration, and gives people the choice to use either negotiation scheme for those things for which either would be usable. Note that, in my opinion, the overlap area in which both TCN and PEP are usable is not very big. It is certainly not so big that one could easily unify the protocols.
Comments are welcome.
This section defines the feature negotiation mechanism. Feature negotiation has been introduced in section 4.8. Appendix 18 contains examples of feature negotiation. We may want to synchronize terminology. As feature creation will be an ongoing process, it is generally not possible for a user agent to know the meaning of all feature tags it can possibly encounter in a variant description.