I think RFC covers this: From http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html Section "9.1.2 Idemp

I think RFC covers this: From http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html Section "9.1.2 Idempotent Methods". "However, it is possible that a sequence of several requests is non- idempotent, even if all of the methods executed in that sequence are idempotent." As well section "9.7 DELETE". The last sentence: Responses to this method are not cacheable. The same in human language: there is no guarantee that you are deleting the same object because its ID matches. E.g. MD5 collisions are rare but they sometimes happen.