ERW: The Manual
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isa

Name

isa -- A reference to a supertype.

Synopsis

An entity type can inherit attributes and relationship types from any number of supertypes. The isa element specifies a supertype of an entity type.

Attributes

entref

The identifier of the entity this element points to.

Reification

When you specify that A is a B ERW keeps in sync the tables reifying the two types (i.e., for each entity in A there is a corresponding entity with the same id in B). Whenever you edit an entity of type A, independently of whether you are editing it in the context of A or B, ERW knows that it is of type A and acts accordingly.

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