draft-snell-http-prefer: Preference-Applied

All,

I know its a little late for this feedback, but I thought I'd bring it 
to the list anyways.

The members of the Calendar and Scheduling Consortium (CalConnect) are 
beginning to use the Prefer header fairly heavily based on 
http://tools.ietf.org/html/draft-murchison-webdav-prefer Atour latest 
interop testing session earlier this week, one of the CalDAV client 
authors noticed that the use of the Preference-Applied response header 
by a server is currently documented as a MAY in 
draft-snell-http-prefer.  The ensuing discussion in the room reached a 
consensus of "if a client can't rely on a server returning this response 
header if/when it applies one or more preferences, then its not very 
helpful".

I know that Preference-Applied was reintroduced after a previous 
CalConnect interop session, but I don't recall if the strength of the 
conformance language for Preference-Applied was discussed on the list.  
Was there a compelling reason behind making the use of 
Preference-Applied only a MAY for servers, or can this be changed into a 
SHOULD or MUST?  Or would we be better served adding such language to my 
WebDAV Prefer draft?

Obviously, a server can choose not to apply any client requested 
preferences, but is there a use-case for a server applying a preference 
and not wanting to tell the client that it did so?

Regards,
Ken

-- 
Kenneth Murchison
Principal Systems Software Engineer
Carnegie Mellon University