User Interface Management Systems (UIMS) allow interface designers to create a complete and working user interface. UIMS considered in this article are those based on object oriented technology. Inside the UIMS the interface is described in a distinctive specification language. This specification is then translated in programming toolkit functions. STEP is an ISO standard (ISO 10303) for the computer-interpretable representation and exchange of product data. Within STEP, EXPRESS language is meant to describe object-oriented data models called schemata. For a data management application, user interface can be generated from data schemata. A mapping between EXPRESS language constructions and interactive objects classes can be established. This states the representation rules of an EXPRESS schemata. User interface specification can be inferred from EXPRESS schemata by using the building rules for graphic objects and for objects behaviour. The generation is partly automatic, partly controlled by the designer. The alterations of the building rules enables the designer to work at the meta-generation level. This meta-generation is supported by a structured description of the building rules. The capabilities for meta-generation allow the designer to adapt the generation. The main goal remains the generation of an abstract interface specification. The specification will then be translated into the distinctive toolkit target. Both the generated interface and the building process have reflective aspects.