Metamodel of logical data modeling in System Architect
The image below shows the structure of models and diagrams, and the relationships between them, in a System Architect encyclopedia.
Note Entities and Relationships are the only objects that are represented diagrammatically on ERDs or IDEF1X diagrams. Attributes, access paths, data elements, and project data models are definitions with no corresponding symbol.
The picture above represents:
•each System Architect encyclopedia has 0-to-many project models
•1 project model has 0-to-many ER model diagrams
•1 project model has 0-to-many ER subject area diagrams
•1 entity, attribute, access path, or relationship is represented 0-to-many times in a diagram in a single project model
•1 data element is used by 0-to-many project models, ER diagrams, entities and relationships.
Other rules to keep in mind:
•Relationships between entity pairs are always identical on all diagrams in the same project model in which the entity pair is included.
•Entities, attributes, access paths, and relationships on diagrams in different project models are not the same thing, even if they have the same name. For example, entity Customer in project model Sales Force is not the same object as entity Customer in project model Overseas Markets.
•Each ER model diagram belonging to the same project model can display a different geometric configuration.
