Marc, thanks for the complete remarks. They were very helpful.

One alternative I suggested is something like the following:

(1) The type of the value of the priority field of a thread is left
undefined.
(2) The 'user' defines a THREAD-PRIORITY>? ordering procedure.
(3) To change the priority, you need to use THREAD-PRIORITY-SET!

(1) and (2) could default to values as in the proposal.

But you say (2) can't be done, for the reasons you describe. Pity. (But
I guess we can create an integer priority from anything I can dream up,
including the mythical deadline).

--
Will