EXPRESS_ — EXPRESS MM Issue: Built-in constants are Constants

Beta-2 has a new subclause 9.8: NamedValues, and it contains the definitions of what ISO 10303-11 calls BuiltInConstants. This appears to be the same concept as Constant, except that the names are defined in the language, instead of the Schema. For some reason, clause 12.11 still defines specific Literal values to refer to these NamedValues, instead of just using the ConstantRef concept. Why? Making the NamedValues a kind of Constant would allow the redundant 12.11 to be deleted from the model.

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A Constant is not an Instance; a Constant refers to an Instance (and not always the same instance). A NamedValue is an Instance. The name of a Constant is in some namespace; the name of a NamedValue is a keyword in the language. The model just doesn't correspond.
It is, however, possible to delete "the redundant 12.11". There is no reason to model the specific forms of Literals that denote specific values. It is, however, useful to note that a reference to a NamedValue or to Indeterminate is a Literal.
As the issue observes, the NamedValues are called BuiltInConstants in ISO 10303-11, which suggests that changing the name of the NamedValues Package is appropriate (after deleting the BuiltInConstants package in 12.11).