Typing and subtyping of metamodels

In model-driven engineering, models are considered first-class entities. Model-driven engineering has been around for over a decade. Still, there has not been much work on how to type models or metamodels, which is important to realise true model-driven software development. In this paper, we discuss how a metamodel can be typed by means of an enclosing class whose state can be utilised by tools such as editors and interpreters. This allows using established object-oriented mechanisms on the metamodel level and supports specialisation of metamodels.