Extension of STEP for the Representation of Parametric and Variational Models

The International Standard STEP (ISO 10303) is intended to facilitate the exchange of data between CAD systems. The first release of the standard, which occurred in 1994, allows the transfer of geometric product models in terms of geometry and topology alone. Since most CAD systems now allow the creation of parametric, constraint-based and feature based models, it is necessary to extend STEP to take into account these newer capabilities. What follows is a discussion of some of the considerations which have arisen in the early stages of this work.