SMM11 — The measurand of Measurement, which references Element (MOF), is owned by Measurement

The measurand of Measurement, which references Element (MOF), is owned by Measurement. It should instead be owned by the association between Measurement and Element. This means that metamodels, such as VDML, extending SMM are able to create their own more specialized associations to restrict the measurand to be typed by metaclasses in their own metamodel. Otherwise they will need to specialize Measurement (SMM) itself – and, what is so awkward, specialize all the subclasses of Measurement (e.g. via multiple inheritance). By specializing only the association they can reuse the SMM Measurement class and all its SMM subclasses with no change. The root constraint underlying all the above is that MOF/UML requires any redefined property to be owned by a classifier that is a generalization of the one owning the redefining property. Note that both associations and classes are classifiers. More specifically, to be able to state that C1:p1

then C2 must be a supertype of C1 (directly or indirectly).

The measurand of Measurement, which references Element (MOF), should instead be owned by the association between Measurement and Element. This means that metamodels, such as VDML, extending SMM are able to create their own more specialized associations to restrict the measurand to be typed by metaclasses in their own metamodel. By specializing only the association they can reuse the SMM Measurement class and all its SMM subclasses with no change.
The root constraint underlying all the above is that MOF/UML requires any redefined property to be owned by a classifier that is a generalization of the one owning the redefining property. Note that both associations and classes are classifiers. More specifically, to be able to state that C1:p1

then C2 must be a supertype of C1 (directly or indirectly).