EXPRESS — Two Subtypes of ActualParameter

In 12.7 Function Calls and 13.7 Procedure Calls, it becomes clear that ActualParameter (12.7.1) is an abstraction of two distinct concepts: One associates an Expression with an InParameter (and behaves like an Assignment) and the other associates a VARExpression with a VARParameter (and behaves more like an AliasStatement). Procedures have both, but Functions have only InParameters, and thus only associations of the first kind. Splitting this concept into its two subclasses would simplify clause 12.7 and clarify clause 13.7.

There is consensus that explicitly modeling "call by value" and "call by reference", which are the two concepts to which the issue refers, is a minor technical change. This change is an improvement in the model that removes a (compliance point) packaging problem, simplifies the text and assists in mappings.