A supertype can only have only one subtype.

More Questions from ER Model and Business Rules

• 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.
• An entity instance of a subtype represents the same entity instance of a supertype.
• Generalization is the process of defining more general entity types from a set of more specialized entity types.
• An entity cluster is a set of one or more entity types and associated relationships.

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