The development of Information Systems (I.S) is of great importance for researchers and industrial users. Different methods for I.S design have been proposed until now. Some of them put emphasis on the statical aspect, and others on the dynamical aspect. A third category of methods has recently appeared, which try to take into account both aspects, and therefore provide an unified view of data and treatments. In addition, there exist approaches that put the stress on rigor in the specification and validation process.This paper presents a Case Tool which constitute a conceptual help to Information Systems design: that tries, on one hand, to handle the statical and dynamical, aspects while providing, at the same time, the user with products that are readables and easy to understood and, on the other hand, to validate the specification obtained in a rigorous way. In fact, it is an attempt to satisfy both the designer and the user.