HP 3000 Manuals HP 3000 Manuals
Chapter 3 Dictionary Architecture Overview The architecture of System Dictionary includes several major components (the E-R model and its components, the core set, domains, versions, security, and the intrinsics) which are all interrelated and work together to provide the benefits listed in Chapter 1. With the exception of the intrinsics, these components are discussed individually in this and the following chapters. This chapter provides a description of the Entity-Relationship Model, the structure on which System Dictionary is based. It also includes information on the individual components that make up this model, and tells how to use them. They are: * Entities * Relationships * Entity types * Relationship types * Relationship classes * Attributes * Type-attribute associations The main purpose of a data dictionary is to provide a mechanism for creating and accessing entities and relationships. Entities and relationships are the definitions that are stored in the dictionary. The other components of the E-R model (entity types, relationship types, attributes, and so on) are structures that support the creation and retrieval of entity and relationship definitions.