A VT-constant is a constant (i.e., not a variable) that denotes a VT-component, or valid value for a VT parameter-slot.
(<=> (Vt-Constant ?Constant) (And (Constant ?Constant) (Value-Type ?Constant Denotation Value-Allowed-For-Vt-Term) (Value-Cardinality ?Constant Denotation 1)))
(Constant ?Constant)
(<=> (Vt-Constant ?Constant) (And (Constant ?Constant) (Value-Type ?Constant Denotation Value-Allowed-For-Vt-Term) (Value-Cardinality ?Constant Denotation 1)))