IFC 4.3.0.1 (IFC4X3_TC1)

# 8.10.3.6 IfcMaterialLayer

## 8.10.3.6.1 Semantic definition

IfcMaterialLayer is a single and identifiable part of an element which is constructed of a number of layers (one or more). Each IfcMaterialLayer has a constant thickness and is located relative to the referencing IfcMaterialLayerSet along the material layer set base (MlsBase).

Air gaps within a material layer set are represented as an IfcMaterialLayer with the attribute IsVentilated having the value TRUE or UNKNOWN. Such air gaps shall be interpreted as voids (not having a material).

The IfcMaterialLayer may have a material layer name which may differ from the IfcMaterial name referenced.

## 8.10.3.6.5 Formal representation

ENTITY IfcMaterialLayer
SUPERTYPE OF (ONEOF
(IfcMaterialLayerWithOffsets))
SUBTYPE OF (IfcMaterialDefinition);
Material : OPTIONAL IfcMaterial;
LayerThickness : IfcNonNegativeLengthMeasure;
IsVentilated : OPTIONAL IfcLogical;
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
Category : OPTIONAL IfcLabel;
Priority : OPTIONAL IfcInteger;
INVERSE
ToMaterialLayerSet : IfcMaterialLayerSet FOR MaterialLayers;
WHERE
NormalizedPriority : NOT(EXISTS(Priority)) OR {0 <= Priority <= 100};
END_ENTITY;