Questions from a new-comer

Hello all,
I know my question can sound "silly" to all of you involved in XP, but I've just joined this ml and I just read the only one official document released by the WG.
In the last we days I received many mail: comments on features or proposals, all referred to as DS5, DS3, DS809, and so on...
But on the Protocol Requirements document I find only Rxxx or DRxxx, never find a DSxxx nor a DSx topic.
Can someone explain me briefly the meaning of all this "DS" and maybe also how does the discussion goes on in the ML?
I'm a student in Italy and I'm doing my bachelor thesis on lightweight communication among different programs made in different ways and on differents platforms. And for the moment I'm just looking around but I think I'll do the examples of how things will work with SOAP since it's the most "famous" of these protocols.

Best Regards to all

Simone
---
Simone Chiaretta
Gallarate (VA) - Italy
THE TRUTH IS OUT THERE