In: Internal report, pages 1-25. University Toulouse 1, October 1992.
Abstract: Petri Nets with Objects (PNOs) is a formalism dedicated to modelling the behaviour of systems where concurrency and interactions between the control structure and the data structure play an important role. It associates Petri Nets and the Object-Oriented approach by replacing the undistinguished tokens of elementary PNs by references towards data structures defined by means of an Object-Oriented data model. Thus, the semantics of PNOs includes a PN aspect (how tokens flow) and an Object aspect (how objects' values are processed). This paper provides the semantics of this formalism.