Concept (concept-oriented model)
- Identity class which is analogous to the reference class in COP, and
- Entity class which is analogous to the object class in COP.
An instance of the identity class is called identity or reference. An instance of the entity class is called entity or object.
Any concept has a parent or base concept which is specified using concept inclusion relation. The inclusion structure of concepts is used for identity modelling. In particular, it defines how data elements are represented.
Each field in the concept entity class is interpreted as a dimension in the multi-dimensional structure. Dimensions are labelled by names which are names of the fields.
A field in the concept entity class has a type specified as some other concept which is referred to as a super-concept (while this concept is called sub-concept). Thus any concept has a number of super-concepts defined by its fields and a number of sub-concepts. The structure of concepts defined by the field types of the entity classes is called is a labelled lattice. In particular, cycles are not permitted and there exist two special concepts:
- top or most general, a direct or indirect super-concept for any other concept, and
- bottom or most specific, a direct or indirect sub-concept for any other concept in the model.
Direct sub-concepts of top concept are referred to as primitive concepts.