On the Semantic Foundations of Standard UML 2.0

This paper provides an overview of the foundations of the run-time semantics underlying the Unified Modeling Language as defined in revision 2.0 of the official OMG standard. One of the problems with the format used for that standard is that the information relating to semantics is scattered throughout the text making it difficult to obtain a global understanding of how the various fragments fit together. This has led many to incorrectly conclude that UML has little or no semantic content. One of the objectives of this paper is to provide a clear and concise description of the structure and essential content of UML runtime semantics. This can serve as a convenient starting point for researchers who want to work on the problem of UML semantics and, in particular, those who are interested in producing formal models of those semantics.