What do we need to say about message paths?

Recall that the original impetus for all this discussion was Noah's
question of how to reconcile multiple receivers with the SOAP processing
model, which clearly describes a single message path from sender to
receiver.  Having explored the implications pretty thoroughly by now, I
think the answer is straightforward: There is one message path per receiver.

We may choose to say more, under various circumstances, but I don't
believe we're obligated to.  If we are so obligated (the precedent of
request-response to the contrary), then I'm quite convinced such an
obligation is independent of how many receivers there might be.  In
other words, allowing for 0 .. N receivers does not open significant
issues w.r.t. message paths and the SOAP processing model.