Representation of constraints in extended transition network for system modelling

We inspect the issues of using extended transition networks as a framework for representing systems development activity. In particular, joint work between the two teams authoring this paper is illustrated. The work on the extensions to the transition network as required for systems development (both theoretical and practical aspects) has progressed jointly with work on the further development of Gedblog; the deductive Data Base Management System with graphic leatures developed at IEI-CNR. Many aspects of systems development methods have been discussed; this paper concentrates on the representation of different kinds of constraints, as well as on the definition of a basic framework for semantics interpretation.