Super-to-Subclass or Gen-Spec Relations
Relational databases (RDB’s) and ERA data models support containment or aggregation (isPartOf) relations.
Object-Oriented databases (OODB’s) also support inheritance by means of superclass - subclass (is-a) relations.
Is-a relations are also called generalization - specialization (genspec) relations.
UML and CDIF use different drawing conventions to distinguish gen-spec from isPartOf relations in EERA Diagrams. (BDE uses CDIF’s convention.)