An action semantics for MML.

This paper describes an action semantics for UML based on the Meta-Modelling Language (MML) - a precise meta-modelling language designed for developing families of UML languages. Actions are de¯ned as computational procedures with side-e®ects. The action semantics are described in the MML style, with model, instance and semantic packages. Di®erent actions are described as specializations of the basic action in their own package. The aim is to show that by using a Catalysis like package extension mechanism, with precise mappings to a simple semantic domain, a well-structured and extensible model for an action language can be obtained