**IFCREPRESENTATIONRESOURCE**

The data model consists of the following:

*Definition of the IAI*: This schema defines the representation of
shape and topology as important definitional properties for products defined
within the IFC Object Model. The representations characterize certain
properties of a product, and any product can be defined by zero, one, or many
of those properties. The schema defines two ways to represent definitional
properties of products:

- topological representation
- geometric shape representation

The geometric shape representation allows for

- multiple shape representations for the same product definition shape
of a product
- separate shape representations for components or parts of the product
definition shape by using shape aspects

The following parts of ISO10303, STEP, had been reviewed to provide
input into the specification of the representation resource for the IFC Object
Model:

*Part 41*, Integrated Generic Resources – Fundamental of
Product Description and Support product_property_definition_schema
product_property_representation_schema
*Part 42*, Integrated Generic Resources – Geometric and
Topological Representation geometry_schema
*Part 43*, Integrated Generic Resources – Representation
Structures representation_schema

Please note, that the above listed resources which are defined within
Integrated Resources of STEP had been interpreted to fit into the IFC
architecture.

**Interfaced schemas (2):**

**Entities (7):**

**Functions (1):**