Graphic Representation of Entities

In data models, entities are generally depicted as rectangles (or rectangles with rounded edges) with their names inside, such as in this figure, where there are 3 entities: Student, Course and Instructor.

Definition of Entities

Entity definitions are essential contributors to the business value of any data model. They are core Metadata. High quality definitions clarify the meaning of business vocabulary and provide rigor to the business rules governing entity relationships. They assist business and IT professionals in making intelligent and application design decisions. High quality data definitions exhibit three essential characteristics:

• Clarity: The definition should be easy to read and grasp. Simple, well-written sentences without obscure acronyms or unexplained ambiguous terms such as sometimes or normally.

• Accuracy: The definition is a precise and correct description of the entity. Definitions should be reviewed by experts in the relevant business areas to ensure that they are accurate.

• Completeness: All of the parts of the definition are present. For example, in defining a code, examples of the code values are included. In defining an identifier, the scope of uniqueness is included in the definition.