capability sets

the one in the base spec now, is technology specific, so it will
need to be moved to the packet based spec.

2 questions:

-should each technology have a specific capability
set definition.  i think so, but am interested in hearing other 
opinions.

-can it remain the fixed size?
[capset id, traffic flags]
[tech specific]
[tech specific]

the capset id would be subdivided to allow each technology
its own range.

or should it be variable?
i.e.
[capset id, length]
[flags, tech specific]
   .
   .
[tech specific]

opinions please?  i tend toward the fixed option,
but if there is a good reason for a variable length
block, please let me know.

i am especially interested in hearing from the
tech specific design teams.

thanks
a.