Enhancing the template mechanism.

MDA needs to utilize a variety of modelling languages in order to be successful. It is widely acknowledged that there is a need to be able to systematically create such modelling languages with much of the research in this area being in the context of transforming the UML into a `family of languages'. Although some progress has been made towards this goal with the introduction of technologies such as templates and package extension, the overall approach has been rather simplistic and coarse-grained. In this paper we introduce, and formally define via a specialized calculus, an extension to the template mechanism which allows more complex templates to be constructed