In entity–relationship (ER) modeling, which type of entity sits above two or more related, more specialized entity types, where those specialized types have attributes that apply to some but not all instances of the broader entity?

Introduction / Context:
In logical data modeling, designers often face situations where one real-world concept has common attributes plus additional attributes that only apply to certain variations. The ER solution is to use supertype–subtype structures, with a shared supertype and one or more specialized subtypes.

Given Data / Assumptions:

• A broad entity has attributes common to all instances.
• Two or more associated specialized entities each carry attributes relevant only to a subset of instances.
• We want the term for the broader, generalized entity.

Concept / Approach:
A supertype captures common attributes and relationships; subtypes capture specialized attributes and possibly specialized relationships. A discriminator on the supertype can indicate which subtype an instance belongs to. This supports clarity, avoids NULLs for inapplicable attributes, and enables inheritance-like behavior in the schema.

Step-by-Step Solution:

Verification / Alternative check:
Supertype–subtype hierarchies are standard in ERD notation (e.g., Chen or Crow’s Foot) for modeling generalization/specialization.

Why Other Options Are Wrong:
Subtype entity: Refers to the specialized, not the generalized, entity.
Archetype entity: Not a standard ER term for this structure.
Instance entity: Refers to an occurrence, not a type.
Associative entity: Used to resolve many-to-many relationships, not specialization.

Common Pitfalls:
Putting subtype-only attributes on the supertype leads to sparse columns and integrity issues. Always push specialized attributes into subtypes.

Final Answer:
Supertype entity