The key purpose of the class diagram is to depict the relationships among the critical data entities (or classes) within the enterprise. This diagram is developed to clearly present these relationships and to help understand the lower-level data models for the enterprise.
The TOGAF class diagram as defined is situated at an early, conceptual stage. The highest level allows the essential business notions of enterprise to be represented, without being distracted by organizational or historical complexities specific to each organization. This conceptual level enables you to think about the business, in order to define an ideal organization with regard to this particular business. These entities will be used to define business processes (products handled by processes), and will be derived to define service application components, exchange data between services and repository data schemas.
Main business entities of the DiscountTravel domain, and their relationships
Business Entity: Describes the semantics of the entities in the business, independently of any IS consideration (e.g. storage, technology, etc.).
Business Entity (developed form): It also presents here one attribute, that is one property that the entity may have.
Association between two classes. An association has a name, and provide at each end the role name, and the cardinalities (possible number of occurrences) of related elements.