ISO 10303-204:2002 specifies the use of the integrated resources necessary for the scope and information requirements for the use and exchange of boundary representation solid models in the mechanical engineering design context.

This document describes an application reference environment for the generation and exchange of volume-based design data in the computer-aided mechanical design process, together with appropriate data models and a physical file implementation form. The information model supports all geometric and topological aspects of a complete description of the shape and size of an object. It was originally developed for applications in mechanical engineering design using the CAD modelling technique boundary representation (B-rep) solid modelling and may be appropriate for other application areas using this technique.

The following are within the scope of ISO 10303-204:2002:

• Three types of B-rep model that are used to represent shape:
  1. faceted B-rep model;
  2. B-rep model with elementary surfaces;
  3. B-rep model with sculptured surfaces;
• curve and surface geometry;
• curves defined in parameter space (pcurves);
• manifold topology;
• product identification information;
• the association of simple presentation attributes such as line-style, line-width, colour with an entire B-rep model, or, with geometric or topological elements of a B-rep model;
• preservation of user-defined names of objects;
• units and measures associated with geometric elements;
• assemblies of parts and sub-assemblies.

The following are outside the scope of ISO 10303-204:2002:

• Other types of shape representation:
  1. wireframe models;
  2. surface models;
  3. geometrically trimmed curves and surfaces;
  4. constructive solid geometry models;
  5. compound B-rep models.
• Geometric and topological data:
  1. 2D geometry, other than for the definition of pcurves;
  2. self-intersecting geometry;
  3. non-manifold topology.
• Dimensioning;
• Tolerances;
• Manufacturing information;
• Advanced presentation features such as multiple views, character fonts and symbols.