ABSTRACT
This chapter reviews the overall structure of international standards organization-standard for the exchange of product model data (ISO-STEP) and its approach to data exchange. It surveys the various languages—specifically Nijssen's information analysis method (NIAM), EXPRESS and EXPRESS-G—that are used in developing specifications within STEP and also some of the tools available for implementing STEP-based translators. The STEP description methods address several different aspects of the specification of a data exchange process. The two most widely used aspects are the description methods used for defining application reference model (ARM) and the description methods used for defining application interpreted model. ARMs are typically defined in either the NIAM information modeling language or EXPRESS-G. EXPRESS is the language developed within the ISO-STEP community for representing application interpreted models. Attributes in EXPRESS are of three general kinds: explicit; derived; and inverse. EXPRESS-G, is a graphical implementation of EXPRESS.
