IfcPropertySingleValue

Semantic definitions at the entity

Entity 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 overriden by assigning an Unit.

The unit is handled by the Unit attribute, see Table 113 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 113 — Single value properties with values, measure types and units

HISTORY New entity in IFC1.0.

IFC2x CHANGE Entity has been renamed from IfcSimpleProperty.

IFC2x3 CHANGE Attribute NominalValue has been made OPTIONAL with upward compatibility for file based exchange.

Attribute definitions

#	Attribute	Type	Cardinality	Description	B
3	NominalValue	IfcValue	[0:1]	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.	X
4	Unit	IfcUnit	[0:1]	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.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	B
IfcPropertyAbstraction
IfcProperty
1	Name	IfcIdentifier	[1:1]	Name for this property. This label is the significant name string that defines the semantic meaning for the property.	X
2	Description	IfcText	[0:1]	Informative text to explain the property.	X
	PartOfPset	IfcPropertySet @HasProperties	S[0:?]	Reference to the IfcPropertySet by which the IfcProperty is referenced.
	PartOfComplex	IfcComplexProperty @HasProperties	S[0:?]	Reference to the IfcComplexProperty in which the IfcProperty is contained.
IfcSimpleProperty
IfcPropertySingleValue
3	NominalValue	IfcValue	[0:1]	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.	X
4	Unit	IfcUnit	[0:1]	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.	X

Formal representations

XSD Specification

 <xs:element name="IfcPropertySingleValue" type="ifc:IfcPropertySingleValue" substitutionGroup="ifc:IfcSimpleProperty" nillable="true"/>

 <xs:complexType name="IfcPropertySingleValue">

  <xs:complexContent>

   <xs:extension base="ifc:IfcSimpleProperty">

    <xs:sequence>

     <xs:element name="NominalValue" nillable="true" minOccurs="0">

      <xs:complexType>

       <xs:group ref="ifc:IfcValue"/>

      </xs:complexType>

     </xs:element>

     <xs:element name="Unit" nillable="true" minOccurs="0">

      <xs:complexType>

       <xs:group ref="ifc:IfcUnit"/>

      </xs:complexType>

     </xs:element>

    </xs:sequence>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcPropertySingleValue

 SUBTYPE OF (IfcSimpleProperty);

  NominalValue : OPTIONAL IfcValue;

  Unit : OPTIONAL IfcUnit;

END_ENTITY;

 EXPRESS-G diagram

Item	SPF	XML	Change	Description
IFC4 to IFC4 ADD1
IfcPropertySingleValue
HasConstraints			ADDED
HasApprovals			ADDED

	Merkmal mit Einzelwert
	Property Single Value
	Propriété à valeur simple