IFC 4.3.0.1 (IFC4X3) development

# 8.10.3.18 IfcMaterialUsageDefinition

ABSTRACT This definition may not be instantiated

## 8.10.3.18.1 Semantic definition

IfcMaterialUsageDefinition is a general supertype for all material related information items in IFC that have occurrence specific assignment parameters to assign a set of materials with shape parameters to a reference geometry item of that component.

There are two ways of assigning a set of materials with shape parameters:

• a layer set to a reference curve - assigning a material layer set with material layers having a sequence and thickness parameter to a reference curve of an element - represented by the 'Axis' shape representation of that element
• a profile set to a cardinal point - assigning a material profile set with assigned profile geometry and insertion points to a reference curve by an offset, called "cardinal point" - the reference curve is represented by the 'Axis' shape representation of that element

Each instantiable subtype of IfcMaterialUsageDefinition has to be assigned to a subtype of IfcElement by using the objectified relationship IfcRelAssociatesMaterial; it is only valid in conjunction with an element occurrence.

Informal Propositions:

1. It is illegal to assign a subtype of IfcMaterialUsageDefinition to a subtype of IfcElementType, it shall only be assigned to an element occurrence.

## 8.10.3.18.4 Formal representation

ENTITY IfcMaterialUsageDefinition
ABSTRACT SUPERTYPE OF (ONEOF
(IfcMaterialLayerSetUsage
,IfcMaterialProfileSetUsage));
INVERSE
AssociatedTo : SET [1:?] OF IfcRelAssociatesMaterial FOR RelatingMaterial;
END_ENTITY;