Approach

The PMI project was created to address this set of concerns. The PMI project participants include industry represented by the Long Term Archiving And Retrieval (LOTAR) consortium, that is comprised of many of the aerospace companies worldwide{#69413}; the project includes CAD suppliers represented by the CAX-IF{#63275}, which is a software interface implementation forum supporting product data exchange standards. The PMI project included requirements from model based design product data definition practices, dimensional tolerances, and geometrical tolerances of form, orientation, location and runout. Requirements for datums, datum systems and tolerance frames were included. Existing capabilities of STEP were compared to the requirements defined by the updated documents and extensions were created as needed. The use of the EXPRESS{#2616} SELECT and SUBTYPE constructs in extensions to existing constructs were proposed to provide upward compatibility.

Scope and contribution

This document describes the development history and process, includes a description of the management data common in the distributed enterprise, identifies EXPRESS ENTITY types that are deprecated in the second edition of ISO 10303-47, describes the structure of the new datum_system ENTITY type, describes some of the improvements in dimensional tolerancing and in geometrical tolerancing, and identifies future research opportunities.