The shape of products may be represented in multiple ways for different purposes. Each representation has a well-known string identifier and a particular representation context. There may be multiple representation contexts to describe a shape at various levels of detail. Most building elements have a 'Body' representation which defines or approximates the physical shape and volume. In addition to physical building elements, non-physical elements may have representations such as spaces and openings.
The following diagram shows the generic classes and relationships used when applying this concept.
In addition, concepts may have particular importance to common or standardised industry practices and scenarios. For these specific usage scenarios, the table below shows a recommended list of general usage patterns that users may adopt.