cat 3560 mls qos - clarification needed

Hello experts,

I need some clarification regarding how QoS is handled internally in 3560
hardware.

I understand, that when packet comes to ingress ports, switch is about to:
- classify packet (assign internal QoS label)
- police/mark traffic
- queue trafic to one of two ingress queues (just before internal ring).

Classification:
If we trust CoS, then the mapping table cos-dscp is used. When we trust IP
Prec, then table ip-prec-dscp is used. When we want to trust DSCP, then
either no map is used, or switch use dscp-mutation map (in reverse order -
on incoming packets).
Policing/marking
If packet exceeds given parameters, switch can drop them or use policed-dscp
map to generate new dscp value.

Now everything I just mentioned bring us to the dscp "label", but when it
comes to queue ingress packeets, there are two maps: cos-input-q and
dscp-input-q.
What exactly is this "QoS label" thing? What is the format? Can we find
inside dscp or cos value? Maybe both of them?
As you can see in the classification/policing/marking - everything goes down
to the dscp. Even more - with marking, we cannot use anything else than dscp
on the map input.

When would be cos-input-q map used, and when dscp-input-q? How it is
connected to this internal dscp label?
Exactly the same question connected to output queueing. There are two maps:
cos-output-q and dscp-output-q.

My thought process so far was: grab the packet, do whatever you need to do
to generate internal dscp value, do whatever you want to do based on this
dscp value, at the end put this dscp value to the packet (maybe using dscp
mutation map) and generate CoS label accordingly (dscp-cos map) if needed.
But I'm affraid, that I missed something important out there.

tia,

-- 
Jakub Drwal
Blogs and organic groups at http://www.ccie.net