ON modularity for conceptual data models and the consequences for subtyping, inheritance and overriding

The binary relationship model is used to explain the principles of schema object types (SOTs). A SOT is a modularization concept for conventional conceptual data models, based on decomposition and abstraction from context. A SOT is at one level a single object type, but at a lower level it is described by a conceptual schema itself. The issue of subtyping, inheritance, and overriding for SOTs are discussed. The relevance of SOTs for object-oriented models is indicated