Entity Definitions

Defining the entities in your logical model is essential to the clarity of the model and elaborates on the purpose of the entity. Defining entities also clarify which facts you want to include in the entity. Undefined entities or attributes can be misinterpreted in later modeling efforts, and possibly deleted or unified based on the misinterpretation.

Writing a good definition can be difficult. The best definitions are created using the points of view of many different business users and functional groups within the organization. Definitions that can pass the scrutiny of many disparate users provide a number of benefits including:

• Clarity across the enterprise
• Consensus about a single fact having a single purpose
• Easier identification of categories of data

Most organizations and individuals develop their own conventions or standards for definitions. Long definitions tend to take on a structure that helps the reader to understand the �thing� that is being defined. Some of these definitions can go on for several pages (CUSTOMER, for example). Because IDEF1X and IE do not provide standards for definitions, you can adopt the following items as a basic standard for definition structure:

• Description
• Business example
• Comments