[Standards] Presence extensions

[Remko Tronçon]

> Ian suggests we need to figure out what to do here and edit RFC3920bis
> accordingly. Probably XEP-0045 needs some updated examples, too.

I can see why this should be clarified in XEP-0045, but I don't see
where the RFC comes into play? At the basic level, servers and clients
should always assume that the information in one presence packet is
'complete', unless the server and/or client explicitly publishes
support for a special protocol where presence-based information can be
left out of presence packets. This should stay at the extension-level,
and the core protocol should remain as simple as possible (to ensure
extensibility and ease of implementation). Or am I misunderstanding
your intentions?

cheers,
Remko