ABSTRACT
The EXPRESS product modeling language is a core capability developed within STEP to define and implement product models. It provides the syntactic features used to define the semantics of STEP product models of all types—electrical, construction, manufacturing, and so forth. It also has been used by most recent efforts in building product modeling, including the IAJ effort, RATAS, CIMsteel and COMBINE. The product modeling strategy of ISO-STEP is to define a neutral model, to and from which various external applications can translate data. Computer languages can be distinguished in terms of declarative and procedural components. An important recognition regarding model changes is that product models involve complex structures that make deletions especially problematic. The View capability is an important aspect of all modern database management systems. The language functionality issues reviewed can only be resolved by both respecting the role of EXPRESS and thinking strategically regarding the evolution of its role in the overall data exchange process.
