Now when someone goes to the server's canonical URI you'll get a full AS2 object (or whatever) in some normalized form. The details don't matter so long as the canonical_uri matches the id.
So you can see how this starts to develop:
Alice sends Bob a message saying that she created a Note (1).
Alice sends Bob a message saying that she created a Note (2).
Alice sends Bob a message saying that she created a Note (3).
Alice sends Bob a message saying that she updated a Note (1).
4/