A visual modelling language for EXPRESS schema

ISO 10303 is the set of standards that define the Product Data Exchange using STEP or PDES. Part 11 of the standard is the EXPRESS modelling language, an object-oriented modelling language upon which the application protocols for data exchange are based. To display and analyse EXPRESS schema, ISO 10303 contains a graphical depiction of a subset of EXPRESS, termed EXPRESS-G. When using EXPRESS-G to design large schema, the authors have found it to be limited in visualizing and interpreting the schema and the implied relations between entities and types. This paper presents a graphical language for designing schema to be represented in EXPRESS. A cross between EXPRESS and more traditional ER modelling approaches, Visual-EXPRESS is a more compact diagram when compared to EXPRESS-G. The specification for Visual-EXPRESS also includes the algorithm to convert the graphical schema into a legal EXPRESS schema.