Class and Package Diagram Consistency

The discussion of Pull #22 reveals some apparent inconsistency in the requirements for Class Diagram and Package Diagram, both internally within the UML Light product and also in comparison with Papyrus UML.

In particular, there are two questions that need answering:

• what is the purpose of supporting the visualization of packages in a UML Light class diagram? Is it only for the relation of packages to the classifiers presented in the diagram (usually namespace/containment), or is it also to present relationships between packages? In the latter case, should the UML Light class diagram then allow the creation/visualization of PackageImport relationships?
• in the Papyrus UML product, the Package Diagram is defined as a strict subset of the Class Diagram. This implies that, deliberately or not, the Class Diagram in Papyrus UML is a superset of the Package Diagram. As such, it allows creation/visualization of PackageImport relationships and the "containment link" connector that the UML Light variant of the Package Diagram supports but not its Class Diagram. Do we want the same subset relationship between these diagrams in UML Light as in Papyrus UML?

Start by reviewing Pull #22 and the current UML Light Class Diagram and Package Diagram requirements, then compare them with the Papyrus UML behavior described here. Done means the project has decided whether package relationships and PackageImport are supported and whether the Class Diagram is a superset of the Package Diagram, with those requirements recorded.