This standard specifies the Unified Modeling Language (UML) with the objective of providing system architects working on object analysis and design with one consistent language for specifying, visualizing, constructing, and documenting the artifacts of software systems, as well as for business modeling. This standard represents the convergence of best practices in the object-technology industry. UML is the proper successor to the object modeling languages of three previously leading object-oriented methods (Booch, OMT, and OOSE). The UML is the union of these modeling languages and more, since it includes additional expressiveness to handle modeling problems that these methods did not fully address. One of the primary goals of UML is to advance the state of the industry by enabling object visual modeling tool interoperability. However, in order to enable meaningful exchange of model information between tools, agreement on semantics and notation is required. UML meets the following requirements: • Formal definition of a common object analysis and design (OA&D) metamodel to represent the semantics of OA&D models, which include static models, behavioral models, usage models, and architectural models. • IDL specifications for mechanisms for model interchange between OA&D tools. This document includes a set of IDL interfaces that support dynamic construction and traversal of a user model. • A human-readable notation for representing OA&D models. This document defines the UML notation, an elegant graphic syntax for consistently expressing the UML's rich semantics. Notation is an essential part of OA&D modeling and the UML.