[Ietf-caldav] authorization identity

[Arnaud Quillaud]

For connection oriented protocols, SASL defines the notion of authorization identity (http://tools.ietf.org/html/rfc4422#section-3.4.1). 
This allows to authenticate as one user and then "switch identity" to act as another user for all following operations (of course assuming that the authenticated user has the right to act on behalf of the other user).

HTTP and HTTP Basic authentication (http://tools.ietf.org/html/rfc2617) which is more or less the only auth mechanism supported by CalDAV do not seem to include such functionality.

Is the functionality actually defined somewhere else or is it missing from HTTP/WebDAV/CalDAV ? Is any CalDAV client/server using proprietary mechanism (e.g. simple http header) to achieve the same result ?

Thanks,

Arnaud Q