Abstract
This paper presents an approach to the construction of a task model of a method, named TOOD (Task Object Oriented Design), used for the development of an interactive system. This approach is based on a formal notation, which gives quantitative results which may be checked by designers and which provide the possibility of performing mathematical verifications on the models. The modelling formalism is based on the joint use of the object approach and high level Petri nets. The concepts borrowed from the object approach make it possible to describe the static aspects of tasks and the Petri nets enable the description of dynamics and behaviour. We also describe a software aid toot for the manipulation of these models, which allows the editing and the simulation of a task model. In order to facilitate the comprehension of the method, an extremely simple example of the air traffic control will be given.