## 5.2 IfcProductExtension

### 5.2.1 Schema Definition

The IfcProductExtension further specialises the concepts of a (physical) product, i.e. a component likely to have a shape and a placement within the project context. The product information is provided for individual product occurrences as subtypes of IfcProduct, and for common specific product types as subtypes of IfcTypeProduct. Both definitions are rooted in supertypes provided within the IfcKernel. Basis concepts, introduced within the IfcProductExtension, are:

- the spatial project structure,
- the element,
- the grid,
- the port, and
- the annotation.

The spatial project structure defines

- the site,
- the building,
- the building storey, and
- the space

and its decomposition structure. In addition the concepts of system and zone are introduced within the IfcProductExtension. Relationships between the spatial structure and the elements are defined, such as spatial containment and space boundaries.

An element is assigned to the spatial project structure and may refer by its placement to a grid. Basic types of elements, which are introduced are

- building element
- opening element
- furnishing element
- distribution element (including heating, ventilation, air conditioning, electrical and equipment elements)
- transportation element

The other concepts introduced are

- a grid, providing a contraint placement for elements,
- an annotation to capture any additional annotations to a building model or plan (such as explanatory text, dimensioning, etc.), and
- a port, providing connectivity between elements.