LCUP: cookie schemes, why?

The document doesn't adequately describe why cookie schemes
are necessary...  in particular, why would a client ever
want to request a particular scheme?  How would a client
determine which schemes where supported by the server?  And,
if the server is allowed to support differ schemes in different
subtrees, how would a client determine which schemes where
supported in which subtrees. 

From past discussions, the main purpose of the scheme was
to facilitate protocol operations in replicated environments.
That is, where the client resumes an LCUP session on a
different server then that which provided the cookie, the
scheme allows the server to determine the cookie format
used by the other server.  If the doesn't recognize the
scheme, it can return an error (or a referral to the
servers which do understand the scheme?).

I don't see any need to allow the client to request
particular cookie schemes.  If there is a need for this,
then we need to make sure adequate discovery mechanisms
are provided so that client can which schemes are supported
where (yuk).  If there is no reason, I suggest that no
means be provided to allow a client to request a particular
scheme.  If later some need arises, LCUP can be extended.
That extension would have to deal with scheme discovery
issues.

Kurt