Absolutely not. The fact that the request-URI is to be the new home of the entity being PUT is the thing from which correct understanding of PUT is derived. I

Absolutely not. The fact that the request-URI is to be the new home of the entity being PUT is the thing from which correct understanding of PUT is derived. Idempotence is a trivial consequence of that (so not necessary in its own right), and is not sufficient. Read the RFCs.