ISO 10303-42-2003 PDF

Full title and description

Industrial automation systems and integration — Product data representation and exchange — Part 42: Integrated generic resource: Geometric and topological representation. This is the ISO/STEP resource describing the EXPRESS schemas and semantic resources used to represent explicit geometry (points, curves, surfaces, solids) and topology (vertices, edges, faces, shells) for product shape data; PDF editions have been published by ISO and national standards bodies.

Abstract

Specifies the resource constructs for explicit geometric and topological representation of product shape models. It defines geometry primitives (points, vectors, parametric curves and surfaces, splines), topological entities (vertex, edge, face, loops, shells), and geometric model constructs (B‑rep, CSG, swept solids, tessellated geometry) used for exchange and archival of CAD/PMI data.

General information

• Status: Withdrawn (superseded/revised in later editions).
• Publication date: April 2003 (ISO 10303-42:2003).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 25.040.40 (Product data representation and exchange / STEP family).
• Edition / version: Edition 4 (2003 edition).
• Number of pages: 328.

Scope

Defines the integrated generic resource constructs required to represent the geometric and topological aspects of product shape for data exchange: parametric and analytic geometry, spline-based curves and surfaces, point/curve/surface replicas, geometric transformations, topological collections and integrity constraints, and geometric model types (manifold B‑reps, CSG, surface and wireframe models). It excludes geometric tolerances, implicit feature-based representations and non‑parametric procedural geometry.

Key topics and requirements

• Definition of geometry primitives: points, vectors, parametric curves and surfaces, conics, splines and locally refined splines.
• Topology primitives and integrity: vertex, edge, face, loops, shells and constraints to ensure manifold and B‑rep integrity.
• Geometric model constructs: manifold boundary representations (B‑rep), constructive solid geometry (CSG), swept solids, half‑spaces and tessellated geometry.
• Associations between geometry and topology (vertex_point, edge_curve, face_surface) and domain concepts for consistent embedding of geometry in topology.
• EXPRESS schema definitions and computer‑interpretable listings for implementation and conformance (used by STEP tools and SMRL collections).

Typical use and users

Used by CAD/CAM/CAE and PLM software vendors, system integrators, data exchange implementers, digital archivists, and standards engineers who implement or map product shape data between systems. Commonly referenced by implementers of STEP application protocols, neutral translators, and by projects that map ISO/STEP resources into other exchange formats (for example IFC or proprietary neutral exchanges).

Related standards

Part of the ISO 10303 (STEP) family. Closely related parts include the EXPRESS and implementation parts (e.g., Parts 11–21) and other integrated resources and application protocols (IR parts 41–62 and APs such as AP203/AP214/AP242). Later revisions and corrigenda of Part 42 (2014, 2018 and subsequent editions) update and consolidate the resource definitions.

Keywords

ISO 10303, STEP, Part 42, geometry, topology, B‑rep, CSG, EXPRESS schema, product data exchange, CAD neutral format, geometric representation.

FAQ

Q: What is this standard?

A: ISO 10303‑42:2003 is the 2003 edition of Part 42 of the ISO 10303 (STEP) family that defines integrated generic resources for geometric and topological representation used to exchange precise product shape data.

Q: What does it cover?

A: It covers EXPRESS schema constructs for explicit geometry (points, curves, surfaces, splines), topology (vertices, edges, faces, shells), and geometric model types (B‑rep, CSG, swept solids, wireframes), plus rules and associations to ensure data integrity during exchange. It does not cover geometric tolerancing or implicit/feature-based representations.

Q: Who typically uses it?

A: CAD/CAM/CAE vendors, PLM and PDM system developers, implementers of STEP translators and application protocols, standards engineers and organizations performing long‑term archival or neutral exchange of CAD models.

Q: Is it current or superseded?

A: The 2003 edition (ISO 10303‑42:2003) has been withdrawn and later revised by subsequent editions and corrigenda. Newer published editions of Part 42 (including editions in the 2010s and a later integrated edition published in 2025) replace the 2003 text; users should obtain the most recent edition for current implementations.

Q: Is it part of a series?

A: Yes — it is Part 42 of the ISO 10303 (STEP) series, which is a large family of parts covering EXPRESS, implementation methods (STEP‑file, SDAI), integrated resources, application protocols (APs) and conformance/test suites for product data representation and exchange.

Q: What are the key keywords?

A: geometry, topology, B‑rep, CSG, EXPRESS schema, STEP, product data exchange, CAD interoperability, geometric model, topology integrity.