Since even before its standardization, the UML has been successfully applied to the development of real-time and embedded systems. The standard types of things one models for schedulability and timeliness analysis include worst case performance, average case performance, and so on. These things are not predefined in the UML, but the UML does provide a means for modeling concurrency (active objects) and another means for modeling the desired timeliness properties (constraints and tagged values).

The Response to the OMG RFP for Schedulability, Performance, and Time or RT UML Profile, is a response to the need to simplify how the analysis of timeliness and schedulability of UML models is done. The RT UML Profile defines standard means for describing the real-time characteristics of the models. While these are likely not superior to the way most real-time developers are doing it today, it does offer the benefit that tool vendors can more easily parse these properties embedded within UML models.