11) Section 4.2.4 and related.
The mechanism around "actualtotalcpucount" to allow
the consumer to determine the number of cpus is potentially 
very powerful. However, the class of parallel applications
which can utilise an arbitrary number of processors is limited.
As geometry-based decompositions are often used for load-balancing
purposes, it's often the case that the application can use
certain numbers of processors but not others. Common patterns
are:
* powers of 2
* powers of 2 and powers of 3 (e.g. 2*3, 2*2*3, 2*3*3)
* powers of 2, 3, and 5
* any of the above plus one (or two), where the one
  processor does some special tasks, like control the
  others, serve random numbers, access a database etc.
I know we discussed this in one of the JSDL sessions
earlier this year. I think it's worth doing if a nice
way can be found of describing contraints on number
of processors. But I won't make a fuss if it remains
out of scope.