There is cardinality on an EER between the supertype and subtype.

More Questions from ER Model and Business Rules

• A supertype is an entity type that shares common attributes or relationships distinct from other subgroupings.
• Total specialization is represented by double lines between the supertype and subtype on an EER.
• 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.
• A subtype discriminator of the supertype is an attribute whose values determine the target subtype(s).
• A supertype can only have only one subtype.
• Packaged data models are meant to be exactly right straight out of the box.
• It is appropriate to use a supertype/subtype relationship when there are attributes that apply to some of the instances of an entity type.
• Action assertions have traditionally been implemented within an application program.
• An ERD that has had the entities clustered will display more entities.
• An action assertion is a statement that expresses some aspect of the static structure of the organization.

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