STEP is an ISO standard (ISO-10303) for the computer-interpretable representation and exchange of product data. Parts of STEP standardize conceptual structures and usage of information in generic or specific domains. The standardization process of these constructs is an evolutionary approach , which uses generated prototypes at different phases of the process. This paper presents a method for the building of prototype generators, inspired by this standardization process, together with a tool used to support the method. Throughout stages of model integration, the embedded logic of prototype generators is defined. The successive stages fo-cuse on data model integration but this integration relies on a common agreement about construct functionalities under elaboration.