What is the top-down process of identifying lower level more specific entity subtypes from a higher level entity Supertype called?

Specialization and generalization are fundamental concepts in database modeling that are useful for establishing superclass-subclass relationships.

Specialization

Specialization is a top-down approach in which a higher-level entity is divided into multiple specialized lower-level entities. In addition to sharing the attributes of the higher-level entity, these lower-level entities have specific attributes of their own. Specialization is usually used to find subsets of an entity that has a few different or additional attributes.

The following enhanced entity relationship diagram expresses the entities in a hierarchical database to demonstrate specialization:

Generalization is a bottom-up approach in which multiple lower-level entities are combined to form a single higher-level entity. Generalization is usually used to find common attributes among entities to form a generalized entity. It can also be thought of as the opposite of specialization.

The following enhanced entity relationship diagram expresses entities in a hierarchical database to demonstrate generalization:

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