Mandatory Extensions in HTTP: Rationale
HTTP servers ignore unrecognized headers
We want requests to fail if the server doesn’t recognize DAV headers
PUT, MOVE, and COPY are affected
3 new methods vs. Mandatory Extensions
3 new methods, especially replacements for DAV methods, seems wrong.
Use the approach being recommended by IETF for extending HTTP.
(Actually, a PUT with a collection as the request-URI probably fails on a plain HTTP server???
It definitely fails on a plain WebDAV server unless a Collection-Member header is present.
So it might be OK to use PUT with Referential-Member header to add referential members.)