RESUMEN
Computer-based counseling systems in health care play an important role in the toolset available for medical doctors to inform, motivate and challenge their patients according to a well-defined therapeutic goal. The design, development and implementation of such systems require close collaboration between users, i.e. patients, and developers. While this is true of any software development process, it can be particularly challenging in the health counseling field, where there are multiple specialties and extremely heterogeneous user groups. In order to facilitate a structured design approach for counseling systems in health care, we developed (a) an iterative three-staged specification process, which enables early involvement of potential users in the development process, and (b) a specification language, which enables an author to consistently describe and define user interfaces and interaction designs in a stepwise manner. Due to the formal nature of our specifications, our implementation has some unique features, like early execution of prototypes, automated system generation and verification capabilities.