This purpose of this standard is to describe the IDEF1X language in an unambiguous manner and thereby meet two important needs. First, those who develop and use IDEF1X models need a common understanding of the modeling constructs and rules. A precise definition of the meaning of the language components allows a model developed by one individual or group to be understood by anotherre. Second, IDEF1X users must be supported in practice by automated tools that record and validate the models. Tool developers need a precise definition of the language so that their products assist users in applying the language correctly and allow exchange of models, at the semantic level, with other tools. The purpose of IDEF1X as a modeling technique is the same as that of all modeling techniques employed in system analysis and development efforts, that is, to plan, build, or use systems and information systems in particular, it helps to understand the meaning of the concepts involved. Modeling provides a "language" for meanings and is sometimes referred to as closing the semantic gap between the concepts of the enterprise and the capabilities of the computer systems. Figure 1 summarizes the fundamental purpose of a model: to enable accurate and useful communication among users, analysts, and developers as they all reason about the same thing.