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. KEY WORDS Tools Rlaintenance FortranBrowsing Graph la!-out

In this paper, a brief description of the VIFOR (Visual Interactive FORtran) environment is given. VIFOR is based on a simple, but effective data model of Fortran programs. The model contains three entity classes and three relation classes only. Programs can be displayed and edited in two forms: the traditional one (i.e. code) and in the visual form. VIFOR contains transformation tools for both directions, i.e. from code to visual form and from visual form to skeletons of code. Hence, it is suitable for reverse engineering and maintenance of existing code. Specially designed browsers implement the graphical interface.

VIFOR is a tool for maintenance of large FORTRAN programs. It contains a database which stores information on all nonlocal declarations of the programs (i.e. subroutines, functions, commons), all source files, and all relations among them, see [ l ] for a detailed description.