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))))))