Diagrams play an important role in the early phases of software development.
All object-oriented methodologies use diagrammatic notations to a large extent. While the syntax of diagrams is becoming standardized by UML, the semantics of these languages is still only vaguely defined. In this talk an approach to defining the semantics of visual languages is introduced, which allows a uniform definition procedure for semantics of different visual languages and thus can also be used for their integration. On the basis of these graphs then abstract automata are defined by using a Z-like notation. These automata define an operational semantics of the language.