VTS volume insert process

[gidonlando]

Hello all,
I've been having real trouble figuring out how exactly does the insert process of a VTS volume work.
The main issue i'm having trouble understanding is the "Volume catagories".
I'd like to know how exactly do "Volume Catagories" in DEVSUPxx help me create partitioning of my VTS and I couldn't find CLEAR documentation of the subject.

Here are a few things i think I understood, if anyone could please fill in the blanks/correct me:
When you insert a logical volume into the VTS you assign it to a scratch "Volume Catagorie". This assignment has to corolate with a "Volume Catagorie" defined in the DEVSUPxx.
Then CBRUXENT exit is invoked which inserts the TAPE to the desired LPAR and defines they're vloume catagorie according to DEVSUPxx.

What I don't quite understand is the significents ot the volume catagorie in the VTS?
What exactly does CBRUXENT update when invoked?
How does DEVSPUxx help with partitioning?

Any help would be apreciated
Thanks in advance.