ISO 10303 (Automation systems and integration — Product data representation and exchange) is a family of ISO standards for computer-interpretable representation (description) and exchange of product manufacturing information (PMI). It aims to provide interoperability between various computer-aided design (CAD) software, assist with automation in computer-aided manufacturing (CAM), and allows long-term archival of 3D, CAD and PDM data. It is known informally as "STEP", which stands for "Standard for the Exchange of Product model data". Due to a large scope ISO 10303 is subdivided into approximately 700 underlying standards total. The standard includes Parts 11-18 and Part 21 that describe EXPRESS data schema definition language and STEP-file (also STEP-XML) used for textual representation of PMI data codified by the standard. These Parts serve as basis for the ISO 10303 and also used by some others standards, such as IFC. Application Protocols (AP) provided by the standard give information for its practical implementation in specific contexts. These describe scope, functional requirements, definitions requirements, and levels of conformance. Notable APs include:
AP238 (STEP-NC) — an underlying standard for CAD-model based CAM and automated CNC machining. AP203 and AP242 — a standard for CAD related data models for CAD data exchange. Excepting few underlying standards ISO10303 is not free and should be acquired via purchasing an individually issued license. NIST (US) has provided various tools to view and analyze (GD&T conformance) STEP files, and work with EXPRESS schema language in VSCode editor.
History The basis for STEP was the Product Data Exchange Specification (PDES), which was initiated during the mid-1980's and was submitted to ISO in 1988. The Product Data Exchange Specification (PDES) was a data definition effort intended to improve interoperability between manufacturing companies, and thereby improve productivity. The evolution of STEP can be divided into four release phases. The development of STEP started in 1984 as a successor of IGES, SET and VDA-FS. The initial plan was that "STEP shall be based on one single, complete, implementation-independent Product Information Model, which shall be the Master Record of the integrated topical and application information models". But because of the complexity, the standard had to be broken up into smaller parts that can be developed, balloted and approved separately. In 1994/95 ISO published the initial release of STEP as international standards (IS) with the parts 1, 11, 21, 31, 41, 42, 43, 44, 46, 101, AP 201 and AP 203. Today AP 203 Configuration controlled 3D design is still one of the most important parts of STEP and supported by many CAD systems for import and export. In the second phase the capabilities of STEP were widely extended, primarily for the design of products in the aerospace, automotive, electrical, electronic, and other industries. This phase ended in the year 2002 with the second major release, including the STEP parts AP 202, AP 209, AP 210, AP 212, AP 214, AP 224, AP 225, AP 227, AP 232. Basic harmonization between the APs especially in the geometric areas was achieved by introducing the Application Interpreted Constructs (AIC, 500 series). A major problem with the monolithic APs of the first and second releases is that they are too big, have too much overlap with each other, and are not sufficiently harmonized. These deficits led to the development of the STEP modular architecture (400 and 1000 series). This activity was primarily driven by new APs covering additional life-cycle phases such as early requirement analysis (AP 233) and maintenance and repair (AP 239), and also new industrial areas (AP 221, AP 236). New editions of the previous monolithic APs on a modular basis have been developed (AP 203, AP 209, AP 210). The publication of these new editions coincided with the release in 2010 of the new ISO product SMRL, the STEP Module and Resource Library, that contains all STEP resource parts and application modules on a single CD. The SMRL will be revised frequently and is available at a much lower cost than purchasing all the parts separately.
2014 updates In December 2014, ISO published the first edition of a new major Application Protocol, AP 242 Managed model based 3d engineering, that combined and replaced the following previous APs in an upward compatible way:
AP 201, Explicit draughting. Simple 2D drawing geometry related to a product. No association, no assembly hierarchy. AP 202, Associative draughting. 2D/3D drawing with association, but no product structure. AP 203, Configuration controlled 3D designs of mechanical parts and assemblies. AP 204, Mechanical design using boundary representation AP 214, Core data for automotive mechanical design processes AP 242, Managed model based 3D engineering AP 242 was created by merging the following two Application protocols:
AP 203, Configuration controlled 3D designs of mechanical parts and assemblies (as used by the Aerospace Industry). AP 214, Core data for automotive mechanical design processes (used by the Automotive Industry). In addition AP 242 edition 1 contains extensions and significant updates for:
Geometric dimensioning and tolerancing Kinematics Tessellation Two APs had been modified to be directly based on AP 242, and thus became supersets of it:
AP 209, Composite and metallic structural analysis and related design AP 210, Electronic assembly, interconnect and packaging design. This is the most complex and sophisticated STEP AP.
2020 updates AP242 edition 2, published in April 2020, extends edition 1 domain by the description of Electrical Wire Harnesses and introduces an extension of STEP modelisation and implementation methods based on SysML and system engineering with an optimized XML implementation method. This new edition contains also enhancements on 3D Dimensioning and Tolerancing, and Composite Design. New features are also introduced:
curved triangles textures levels of detail (LODs) color on vertex 3D scanner data support persistent IDs on geometry additive manufacturing
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