The class of all model fragments that denote operator actions.By convention, devices will have a subclass of this class whose immediate subclasses are all of
the behavior modes of a given device, i.e. Battery-Operating-modes is a superclass of
the overcharged, undercharged etc. modes.
(=> (Model-Class-To-Operate-On $X $Y) (Operator-Action-Model $X)) (=> (Slot-To-Operate-On $X $Y) (Operator-Action-Model $X))