Foundations of Meta-Pyramids: Languages vs. Metamodels - Episode II: Story of Thotus the Baboon1

Despite the recent interest for Model Driven Engineering approaches, the so-called four-layers metamodelling architecture is subject to a lot of debate. The relationship that exists between a model and a metamodel is often called instanceOf, but this terminology, which comes directly from the object oriented technology, is not appropriate for the modelling of similar meta-pyramids in other domains. The goal of this paper is to study which are the foundations of the meta-pyramids independently from a particular technology. This paper is actually the second episode of the series "From Ancient Egypt to Model Driven Engineering". In the pilot episode, the notion of megamodel was introduced to model essential Model Driven Engineering concepts. The notion of models was thoroughly discussed and only one association, namely RepresentationOf was introduced. In this paper the megamodel is extended with one fundamental relation in order to model the notion of languages and of metamodels. It is shown how Thotus the Baboon helped Nivizeb the priest in designing strong foundations for meta-pyramids. The secrets of some ancient pyramids are revealed.