The definition of Integrated Information Systems is not an easy task. In consequence, the development of models is a prerequisite when trying to identify the information requirements of an organization. The complexity inherent to production environments makes the definition of a unique model infeasible. Thus, a three layer architecture is proposed as a framework for building Task, Domain and Dynamic models. Each model focuses on one aspect but all of them are needed to reach an understanding of a particular production domain. This paper introduces a series of primitive constructs that allow the definition of high level classes of models (metamodels). Specifically, it describes in detail the Function-Task Metamodel that is employed to represent the different types of activities that are performed in a Production Enterprise.