When two classes are defined with the same property name and then both class are assigned to a type (which may already have a property with the same name) , the specification does not describe what should happen with the conflicting property name. For example if the model has two ReactorClassTypes - MixingReactorClassType and a HeatingReactorClassType both of which have a TroubleShootingGuide property, when I add both classes to a HeatingMixingReactorType which has a TroubleShootingGuide - what should happen to the three TroubleshootingGuide properties? They are different, but have the same property name. Instances already created from the type have to be updated with the new properties so the conflict resolution process needs to take that into account (browse names and display of properties on instances cannot be changed).

Another aspect of this issue is that the specification does not place restrictions on the DefinedByEquipmentClass reference to prevent Types from getting references from a ClassType and one of its ancestors. This can lead to very complex situations because properties can be overridden by subtypes so a Type could get a property with the same from a ClassType and an ancestor ClassType with different meanings.

A variation on this scenario would be assigning a ClassType (ReactorClassType) to a Type (ReactorType), subtyping both (MixingReactorClassType and MixingReactorType)and assigning MixingReactorClassType to MixingReactorType. What should be the resulting set of properties?