The following sections are provided as a quick reference for those who are not familiar with IDEF1X entity-relationship diagram notation. An entity is defined as a person, place, thing, or concept of interest to an enterprise. Entity names are always singular nouns. IDEF1X distinguishes between independent and dependent entities. Independent entities are defined as entities that depend on no other entity for their identification.
Dependent entities depend on other entities for their identification.
Entities depicted with square corners are independent entities and entities depicted with rounded corners are dependent entities. A prime word represents the logical data grouping and is used in the name of the attributes contained in the entity. Relationships A relationship is a way of depicting a meaningful association between two entities. It may be further described as a rule about how entities work together. Relationships are noted by named lines drawn between entities.