# 7.3.3.3 IfcConstructionMaterialResource

AbRV ⓘ
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## 7.3.3.3.1 Semantic definition

IfcConstructionMaterialResource identifies a material resource type in a construction project.

Occurrences of IfcConstructionMaterialResource are consumed (wholly or partially), or occupied during a construction work task (IfcTask).

Similar to IfcConstructionProductResource, sometimes things such as 5000kg of gravel are already instantiated as an instance of an IfcProduct subtype because it is a result of a work task (for example, transporting gravel). In this case, the instance of IfcConstructionMaterialResource can be associated with the product instance 5000kg of gravel to provide more information for resource uses. Nevertheless, IfcConstructionMaterialResource should only be used to represent resource usage, but not product substances.

## 7.3.3.3.7 Formal representation

ENTITY IfcConstructionMaterialResource
SUBTYPE OF (IfcConstructionResource);
PredefinedType : OPTIONAL IfcConstructionMaterialResourceTypeEnum;
WHERE
CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR
(PredefinedType <> IfcConstructionMaterialResourceTypeEnum.USERDEFINED) OR
((PredefinedType = IfcConstructionMaterialResourceTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
END_ENTITY;