FIXED-LENGTH-JOB-CLASS denotes a job whoes length is independent of a resource and fixed.
(<=> (Fixed-Length-Job-Class ?Class)
(And (Class ?Class)
(Subclass-Of ?Class Job)
(Slot-Cardinality ?Class Fixed-Length-Job.Length 1)))
(Slot-Cardinality ?Class Fixed-Length-Job.Length 1) (Class ?Class)
(<= (Subclass-Of $X Job) (Fixed-Length-Job-Class $X))
(<=> (Fixed-Length-Job-Class ?Class)
(And (Class ?Class)
(Subclass-Of ?Class Job)
(Slot-Cardinality ?Class Fixed-Length-Job.Length 1)))
(<=> (Unit-Length-Job-Class ?Class)
(And (Fixed-Length-Job-Class ?Class)
(Value-Cardinality ?Class Job-Unit-Length 1)
(Forall (?I)
(=> (Instance-Of ?I ?Class)
(= (Fixed-Length-Job.Length ?I)
(Job-Unit-Length ?Class))))))