... performed, the inclusion of IdleProcRef and the ex-clusion of NullProcRef are of some importance. They determine the range of possible values for the domains of the components of process descriptors. ... interruptsoccur during the execution of a piece of code. They are used as a kind of low-level mutual exclusion mechanism.4.3 Common Structures 101Proof. By a previous Lemma (Lemma 5) , | scnt| =#elts.ByLemma6andinduction, ... the idle process, of course.Proof. The components of the process description, pstate, pkind, pstack,pregs, etc., all have identical domains by the first part of the invariant of PROCESSES.Thatis:dom...