„In its current form UML is designed to support a wide variety of different modelling techniques and formalisms. This is evident, for example, in the state machine formalism which allows both Moore and Mealy formalism with hierarchical states including concurrent sub-states and both synchronous and asynchronous calling semantics. The result of this is not only that almost any state modelling style can be supported but also that many combinations of elements have no defined execution semantics. It is now widely recognised within the UML community, however, that considerable benefit can be gained by forming subsets of the UML with well defined execution semantics. Such subsets can form an “executable UML” which would enable the simulation, execution, testing and ultimately translation of UML models into target code. As part of this movement, work is progressing under the auspices of the OMG towards the definition of “profiles” that define such subsets and towards the more detailed definition of the contents of “actions” including a more precise definition of the execution semantics of UML models.“
— Stephen J. Mellor
Mellor and Ian Wilkie (1999). A mapping from Shlaer-Mellor to UML http://www.ooatool.com/docs/SMUML99.pdf. Technical report, Projtech Inc. and Kennedy Carter Limited, 1999.