8.16.3.12 IfcPropertySingleValue

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8.16.3.12.1 Semantic definition

The property with a single value IfcPropertySingleValue defines a property object which has a single (numeric or descriptive) value assigned. It defines a property - single value combination for which the property Name, an optional Description, and an optional NominalValue with measure type is provided. In addition, the default unit as specified within the project unit context can be overridden by assigning an Unit.

The unit is handled by the Unit attribute, see Table A for an example of various single value properties:

If the Unit attribute is not given, then the unit is already implied by the type of IfcMeasureValue or IfcDerivedMeasureValue. The associated unit can be found at the IfcUnitAssignment globally defined at the project level (IfcProject.UnitsInContext).
If the Unit attribute is given, then the unit assigned by the Unit attribute overrides the globally assigned unit.

Name	NominalValue	Type (through IfcValue)	Unit
Description	Manufacturer "A" door	IfcLabel	-
PanelThickness	0.12	IfcPositiveLengthMeasure	-
ThermalTransmittance	2.6	IfcThermalTransmittanceMeasure	W/(m2K)

Table A — Single value properties with values, measure types and units

{ .change-ifc2x}

{ .change-ifc2x3}

8.16.3.12.2 Entity inheritance

8.16.3.12.3 Attributes

#	Attribute	Type	Description
IfcPropertyAbstraction (1)
	HasExternalReferences	SET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjects	Reference to an external reference, e.g. library, classification, or document information, that is associated to the property definition. IFC4-CHANGE New inverse attribute.
IfcProperty (8)
1	Name	IfcIdentifier	Name for this property. This label is the significant name string that defines the semantic meaning for the property.
2	Specification	OPTIONAL IfcText	URI reference to a location with semantic definition or informative text to explain the property.
	HasApprovals	SET [0:?] OF IfcResourceApprovalRelationship FOR RelatedResourceObjects	User-defined approvals for the property.
	HasConstraints	SET [0:?] OF IfcResourceConstraintRelationship FOR RelatedResourceObjects	User-defined constraints for the property.
	PartOfComplex	SET [0:?] OF IfcComplexProperty FOR HasProperties	Reference to the IfcComplexProperty in which the IfcProperty is contained. IFC4-CHANGE The cardinality has changed to 0..n to allow reuse of instances of IfcProperty in several IfcComplexProperty with upward compatibility for file based exchange.
	PartOfPset	SET [0:?] OF IfcPropertySet FOR HasProperties	Reference to the IfcPropertySet by which the IfcProperty is referenced. IFC4-CHANGE New inverse attribute to navigate from IfcProperty to IfcPropertySet with upward compatibility for file based exchange.
	PropertyDependsOn	SET [0:?] OF IfcPropertyDependencyRelationship FOR DependantProperty	The relating property on which the value of the property depends.
	PropertyForDependance	SET [0:?] OF IfcPropertyDependencyRelationship FOR DependingProperty	The property on whose value that of another property depends.
Click to show 9 hidden inherited attributes Click to hide 9 inherited attributes
IfcPropertySingleValue (2)
3	NominalValue	OPTIONAL IfcValue	Value and measure type of this property. NOTE By virtue of the defined data type, that is selected from the SELECT IfcValue, the appropriate unit can be found within the IfcUnitAssignment, defined for the project if no value for the unit attribute is given. IFC2x3-CHANGE The attribute has been made optional with upward compatibility for file based exchange.
4	Unit	OPTIONAL IfcUnit	Unit for the nominal value, if not given, the default value for the measure type (given by the TYPE of nominal value) is used as defined by the global unit assignment at IfcProject.

Table B

8.16.3.12.4 Formal representation

ENTITY IfcPropertySingleValue
SUBTYPE OF (IfcSimpleProperty);
NominalValue : OPTIONAL IfcValue;
Unit : OPTIONAL IfcUnit;
END_ENTITY;

8.16.3.12.5 References

IfcSimpleProperty