Don’t get hung up on UML. Sometimes the fixation on a tool, such as UML diagramming, leads people to distort the model to make it fit what can easily be drawn. For example, UML does have some features for representing constraints, but they are not always sufficient. Some other style of drawing (perhaps conventional for the other paradigm), or simple English descriptions, are better than tortuous adaptation of a drawing style intended for a certain view of objects.
