Preference-Applied Response Header

All,

Its not overly important, but as I was coding this up, I started 
wondering how to categorize this response header in httpbis-22 terms. 
Would this header be considered part of Control Data, Response Context, 
Representation Metadata, or something else?  Right now, I'm leaning 
towards Control Data since Prefer is similar to Expect which is 
categorized as a Control.

And while we're at it, what about these WebDAV response headers:

DAV: similar to Allow => Response Context?

Lock-Token: used in conditional requests => Validator?

-- 
Kenneth Murchison
Principal Systems Software Engineer
Carnegie Mellon University