SMM12 — SMM class for unit of measure of counting measures.

In SMM 1.0, the unit of measure for CountingMeasures was assumed to be their Scope's class. In SMM 1.1, the UnitOfMeasure class was introduced and unit of measure of DimensionalMeasures must be a UnitOfMeasure. These are two different approaches that have not been harmonized in SMM 1.1, but should have been harmonized.

A subclass of UnitOfMeasure is needed to serve as unit of measure for CountingMeasures. This would be a significant convenience anyway and allow constraints which tie the counting back to counting instances of a class or stereotype.

The example given in Figure 9 “CountingMeasure Unit of Measure Constraint” will need to be updated too.

Add CountingUnit Class

Enable that counts can be expressed in terms of Unit of Measure, and for that purpose extend Unit of Measure to create a new class Counting Unit of Measure which has Class and Stereotype attributes just as Scope has.

The counting constraint, then, requires that the Unit is a Counting Unit of Measure. If the unit has a Class then the Scope does and the two Classes must match. Otherwise, the Unit has a Stereotype implying the Scope has a Stereotype and the two Stereotypes must match.