Recently I participated in a discussion of a common problem in data modelling. The question is whether to represent parties (groups) as roles or as subtypes (generalisation hierarchy).

When designing the Conceptual Data Model, parties can be represented as subtypes provided there is a common context amongst sub-types. In the Logical Model, subtypes should be represented only if each subtype has a unique concept that the others don’t.

You can read view the LinkedIn discussion here and/or see my Short notes on Barker’s ERD Notation.