the class of model fragments about a contol-volume
the control volume
(Forall (?Cv-Involved)
(<=> (Control-Volume ?Cv-Involved)
(Exists (?Self)
(And (Control-Volume-Op-Mode ?Self)
(= (Cv-Involved ?Self) ?Cv-Involved)))))
(Forall (?Self ?Time)
(<=> (Active ?Time Control-Volume-Op-Mode ?Self)
(Control-Volume-Op-Mode ?Self)))