The first major revision of the UML standard, UML 2.0, is scheduled for completion in 2003. This paper gives an overview of the most important features of UML 2.0 and the rationale behind them. Special emphasis is given to the application of these features to real-time and embedded system problems. Practical real-world examples are used throughout. The author is one of the primary contributors to this as well as prior versions of UML.