draft-snell-http-prefer

Hello,

I'm working on draft draft-murchison-webdav-prefer which describes how 
the return-minimal and return-representation apply to WebDAV/CalDAV 
methods.  My work is primarily CalDAV-centric but we are trying to make 
it generic to WebDAV and its derivatives.

One of the issues that keeps coming up is a way for the client to 
differentiate between two  cases:

- the server doesn't return a representation because it ignored or 
doesn't support the return-representation preference

- the server understood the preference but didn't return a 
representation because it didn't change from what was in the request

One possible solution is for the server to return a Vary: Prefer header 
to indicate that the server understood the preference, thereby allowing 
the client to infer what the lack of a representation in the response means.

The next question is, does any such mandate or recommendation, if 
required, belong in my webdav-prefer draft or in the base Prefer spec?

Thoughts?

-- 
Kenneth Murchison
Principal Systems Software Engineer
Carnegie Mellon University