[voiceofunreason]

My guess is that if you were building all of this from scratch, you would start with

- request-with-a-body

- idempotent-request-with-a-body

- safe-request-with-a-body

because the additional constraints induce properties that are extremely useful to general purpose clients ("I didn't get a reply to my idempotent-request-with-a-body, can I resend it without risking loss of property?")

Would someone then come along an introduce safe-request-without-a-body method? After all, we can already meet that "need" with safe-request-with-a-body and content-length: 0.

Think rfc-5789::PATCH - mechanically, it's just another request-with-a-body, but with more tightly constrained semantics. But general purpose components can take advantage of the additional properties, and so we introduce a "niche" method with tighter constraints.

Document resource manipulation is a common case, so we probably end up with a family of specialized methods, in much the same way that we have a bunch of WebDAV methods.