Despite the availability of a large number of systems analysis and design methods and techniques there does not exist a general underlying formal foundation for this domain. We present here one effort in this direction. Based on the notion that an information system is a representation of another ('real-world') system, we used ontology, which is the branch of philosophy dealing with modelling reality, to model information systems concepts. The model was based on an ontological formalism by Bunge. The paper describes the fundamental concepts and premises of the model and its main applications. These applications include theoretical analysis, practical guidelines for modelling, and development of prototype systems analysis support tools.
