"The Hypertext Transfer Protocol (HTTP) Extensions for the Web Distributed Authoring and Versioning (WebDAV) do not define the behavior for the ""POST"" method when applied to collections@ as the base specification (HTTP) leaves implementers lots of freedom for the semantics of ""POST"". This has led to a situation where many WebDAV servers do not implement POST for collections at all@ although it is well suited to be used for the purpose of adding new members to a collection@ where the server remains in control of the newly assigned URL. In fact@ the Atom Publishing Protocol (AtomPub) uses POST exactly for that purpose. On the other hand@ WebDAV-based protocols@ such as the Calendaring Extensions to WebDAV (CalDAV)@ frequently require clients to pick a unique URL@ although the server could easily perform that task. This specification defines a discovery mechanism through which servers can advertise support for POST requests with the aforementioned ""add collection member"" semantics."