Extension of ISO 10303, the STEP standard, for the exchange of procedural shape models

The paper describes the status of work aimed at extending the international standard ISO 10303 (STEP) to permit the exchange of procedurally defined shape models between CAD systems. Such models are specified by the sequence of operations used to construct them rather than by the explicit elements they contain. They have the advantage of being easy to edit in a receiving system, by contrast with the explicit models that can be exchanged using current standards, which prove to be inert after transfer. The use of the proposed methodology in the exchange of realistic procedural shape models of mechanical parts has already been demonstrated, and a brief account is given of some of the tests that have been performed.