Right now, there's no way to know the fullUrl of the resource that you're submitting in the same way there is when you pass a transaction or batch to a server. And there are situations where it's useful to know "this resource I just received is known as "[someBase]/Foo/32" if I ever want to grab the current version or translate my id to that server's id when communicating with that server.

Grahame proposed that this could be sent using a separate paired parameter, but that would mean you'd need to separately code the linkage for each parameter for each operation, which seems ugly to me.