International Standard
ISO 10303-42:2022
Industrial automation systems and integration — Product data representation and exchange — Part 42: Integrated generic resource: Geometric and topological representation
Reference number
ISO 10303-42:2022
Edition 7
International Standard
Read sample
ISO 10303-42:2022
Published (Edition 7, 2022)


This document specifies the integrated generic resource constructs for geometric and topological representation.  The following are within the scope of this document:

The following are in the scope of the geometry schema:

  • definition of points, vectors, parametric curves and parametric surfaces;
  • definition of finite volumes with internal parametrisation;
  • definition of transformation operators;
  • points defined directly by their coordinate values or in terms of the parameters of an existing curve or surface;
  • definition of conic curves and elementary surfaces;
  • definition of curves defined on a parametric surface;
  • definition of general parametric spline curves, surfaces and volumes;
  • definition of locally refined spline curves, surfaces and volumes;
  • definition of point, curve and surface replicas;
  • definition of offset curves and surfaces;
  • definition of intersection curves.

The following are in the scope of the topology schema:

  • definition of the fundamental topological entities vertex, edge, and face, each with a specialised subtype to enable it to be associated with the geometry of a point, curve, or surface, respectively;
  • collections of the basic entities to form topological structures of path, loop and shell and constraints to ensure the integrity of these structures;
  • the association of faces with geometric volumes;
  • orientation of topological entities.

The following are in the scope of the geometric model schema:

  • data describing the precise geometric form of three-dimensional solid
  • objects;
  • constructive solid geometry (CSG) models;
  • CSG models in two-dimensional space;
  • definition of CSG primitives and half-spaces;
  • creation of solid models by sweeping operations;
  • manifold boundary representation (B-rep) models;
  • constraints to ensure the integrity of B-rep models;
  • surface models;
  • wireframe models;
  • geometric sets;
  • creation of a replica of a solid model in a new location;
  • tessellated geometry;
  • the association of tessellated geometry with exact geometry.

The following are in the scope of the scan data 3d shape model schema:

  • representation of a shape as a cloud of points produced by a scanning process.

The following are outside the scope of this document:

  • all other forms of procedurally defined curves and surfaces;
  • curves and surfaces which do not have a parametric form of representation;
  • any form of explicit representation of a ruled surface.

    NOTE    For a ruled surface the geometry is critically dependent upon the parametrisation of the boundary curves and the method of associating pairs of points on the two curves. A ruled surface with B-spline boundary curves can however be exactly represented by the B-spline surface entity.

  • spatial occupancy forms of solid models (such as octree models);
  • geometric tolerances;
  • implicit forms of representation in terms of features;
  • assemblies and mechanisms.

General information

  •  : Published
     : 2022-12
    : International Standard to be revised [90.92]
  •  : 7
     : 11
  • ISO/TC 184/SC 4
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This collection is a standard for the exchange of product model data (STEP) module and resource library (SMRL). It is intended for those who are considering adopting ISO 10303 modular application protocols, application modules, and resource parts, or systems built on them, for product data representation …

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