User-Agent Header?

http://www.w3.org/TR/2008/WD-ct-guidelines-20080801/


Section 4.1.3 ...

""'
The mechanism by which a proxy recognizes the user agent as a Web
browser should use evidence from the HTTP request, in particular the
User-Agent and Accept headers.
"""

Please clarify -- is this just the *existence* of those headers, or
the specific values?  If it is the specific values, then please
provide some guidance (or a normative alternative) that new user
agents can use, before their names propagate to various whitelists.

-jJ