An entity cluster is a set of one or more entity types and associated relationships.

Action assertions have traditionally been implemented within an application program.

If an entity adheres to the disjoint rule, then an entity instance can be a member of more than one entity for a given supertype.

It is appropriate to use a supertype/subtype relationship when there are attributes that apply to some of the instances of an entity type.

Generalization is the process of defining more general entity types from a set of more specialized entity types.