The ERA Data Model: Entities, Relations and Attributes
Specifies each Attribute (property or data field) by its Data Type or permitted set of values.
Specifies each Entity, Class or Record type in terms of its component attributes, data members or fields, respectively.
Specifies each Relation type in terms of its component Entity Types or Classes.
Three important questions:
- Can Relation components be nested relation instances?
- Can Relation instances have attributes or properties?
- Can an ERA Data Model be specified by a diagram?