EXPRESS_ — InstantiableType:fundamental-type should be derived

In clause 8.6.7.3, InstantiableType:fundamental-type has multiplicity 1..1. This is semantically correct, but it has the effect of requiring the fundamental-type association to be instantiated for every InstantiableType in every Schema, even though it is only used in evaluating Expressions involving SpecializedTypes. The EXPRESS rule is given in the Definition, and it can be considered to be a (recursive) derivation rule. Making the attribute "derived" in this way removes the requirement for it to be instantiated.

Proposed change: Make InstantiableType:fundamental-type a derived association.

From a semantic point of view, it is a derived attribute, and the derivation rule is stated in the definition. So the change is appropriate in all cases.