[Users] default behaviour

[Mark Kent]

As an educational tool, I'm trying to write a pure proxy using
openser.  This proxy doesn't have users or domains or gateways, 
it just shuffles messages that happen to land on it.

I'm starting with REGISTER where I have simply this:

  t_on_reply("10");
  t_on_failure("10");
  t_relay();

The onreply and onfailure callbacks just log stuff.

The openser cookbook says:

  The implicit action after execution of the main route block is to drop
  the SIP request. To send a reply or forward the request, explicit
  actions must be called inside the route block.

To find what happens in other route blocks (onreply, etc.), I searched
the cookbook for "implicit" and learned:

  implicit action for branch_route is to forward the request.

  implicit action for onreply_route is to send the reply upstream
  according to Via header

And that's all there is.  Is there more written somewhere else?

What I noticed is that informational responses (1xx) are not relayed
by openser, but Final (200) or Client Error (401) are relayed.
Is this conclusion correct?

This implicit behaviour seems a little odd to me;  I would 
think that if I've got a t_on_reply out there then I'm saying
"Hey, I'll handle it" but in fact I cannot handle it (t_relay is
not allowed in an onreply block).

So, I must be missing something in my understanding...
I'ld appreciate it if someone could clarify for me.

Thanks,
-mark