IDEF1X

IDEF1X, or Integrated Definition for Information Modeling, is a data modeling method in the IDEF family designed for the specification, visualization, and design of data structures for information systems. Developed in the 1980s under the United States Air Force's IDEF program, IDEF1X was intended as a more rigorous successor to the earlier IDEF1, emphasizing semantic correctness and compatibility with relational database design.

Key concepts include entity types, attribute types, keys, and relationship types. Entities represent real-world objects or concepts; attributes describe properties; primary keys identify instances. Relationships describe associations between entities and are categorized as identifying or non-identifying, with defined cardinalities such as one-to-one, one-to-many, and many-to-many. The notation supports subtypes and supertypes (generalization/specialization), disjointness and completeness constraints, and derived attributes. IDEF1X also emphasizes normalization, typically guiding models toward relational schemas in third normal form, and it records semantic constraints and business rules that affect data integrity.

Notation and outputs: diagrams express entities, attributes, and relationships in a consistent ER-like style, with keys underlined and relationship types linked to participating entities. Models are intended to be transformable into relational schemas and DDL for database implementation, and they are often accompanied by a data dictionary.

Applications and legacy: used for enterprise data modeling, information architecture, and system integration projects. While tool support and popularity have waned with the rise of UML and other notations, IDEF1X remains a historical reference for formal data modeling and legacy database design.