VIFOR: A tool for software maintenance

VIFOR is a software tool oriented towards maintenance of medium‐to‐large Fortran77 programs. With VIFOR, programs can be displayed and edited in two forms: as the code and as the graph. VIFOR also contains transformations in both directions, i.e. from code to graph and from graph to skeletons of code. Hence, it is suitable for re‐engineering and maintenance of existing code. Specially designed browsers implement the graphical interface. VIFOR contains a database that is based on a simple but effective data model of Fortran programs. The model contains only four entity classes and three relations, which makes the tool small, and easy to implement and use. A simple query language allows browsing through the database.