18.104.22.168.1 Semantic definition
A property with an enumerated value, IfcPropertyEnumeratedValue, defines a property object which has a value assigned that is chosen from an enumeration. It defines a property - value combination for which the property Name, an optional Description, the optional EnumerationValues with measure type and optionally an Unit is given.
The unit is handled by the Unit attribute, see Table 22.214.171.124.A for an example of a enumerated property:
- 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.
More precisely: The IfcPropertyEnumeratedValue defines a property, which value is selected from a defined list of enumerators. The enumerators are stored in a dynamic enumeration of values including the type information from IfcValue (see IfcPropertyEnumeration). This enables applications to use an enumeration value as a property within a property set (IfcPropertySet) including the allowed list of values.
|Name||Value (EnumerationValue)||Type (through IfcValue)||IfcPropertyEnumeration (Name)|
The IfcPropertyEnumeratedValue refers to an IfcPropertyEnumeration, see Table 126.96.36.199.B for an example:
|Name||EnumerationValues||Type (through IfcValue)||Unit|
|DamperBladeActionEnum||(Parallel, Opposed, Other, Unset)||IfcString||-|
It is not mandatory to use an instance of IfcPropertyEnumeration to hold the applicable values for IfcPropertyEnumeratedValue, however this is the preferred way. A single instance of IfcPropertyEnumeration can be referenced by multiple instances of IfcPropertyEnumeratedValue.
188.8.131.52.2 Entity inheritance
|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.
Name for this property. This label is the significant name string that defines the semantic meaning for the property.
URI reference to a location with semantic definition or informative text to explain the property.
|PartOfPset||SET [0:?] OF IfcPropertySet FOR HasProperties||
Reference to the IfcPropertySet by which the IfcProperty is referenced.
|PropertyForDependance||SET [0:?] OF IfcPropertyDependencyRelationship FOR DependingProperty||
The property on whose value that of another property depends.
|PropertyDependsOn||SET [0:?] OF IfcPropertyDependencyRelationship FOR DependantProperty||
The relating property on which the value of the property depends.
|PartOfComplex||SET [0:?] OF IfcComplexProperty FOR HasProperties||
Reference to the IfcComplexProperty in which the IfcProperty is contained.
|HasConstraints||SET [0:?] OF IfcResourceConstraintRelationship FOR RelatedResourceObjects||
User-defined constraints for the property.
|HasApprovals||SET [0:?] OF IfcResourceApprovalRelationship FOR RelatedResourceObjects||
User-defined approvals for the property.
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|3||EnumerationValues||OPTIONAL LIST [1:?] OF IfcValue||
Enumeration values, which shall be listed in the referenced IfcPropertyEnumeration, if such a reference is provided.
Enumeration from which a enumeration value has been selected. The referenced enumeration also establishes the unit of the enumeration value.
184.108.40.206.4 Formal propositions
Each value within the list of EnumerationValues shall be a member of the list of EnumerationValues at the referenced IfcPropertyEnumeration (provided that both, the EnumerationValues and EnumerationReference, are asserted).
220.127.116.11.5 Formal representation
ENTITY IfcPropertyEnumeratedValue SUBTYPE OF (IfcSimpleProperty); EnumerationValues : OPTIONAL LIST [1:?] OF IfcValue; EnumerationReference : OPTIONAL IfcPropertyEnumeration; WHERE WR21 : NOT(EXISTS(EnumerationReference)) OR NOT(EXISTS(EnumerationValues)) OR (SIZEOF(QUERY(temp <* EnumerationValues | temp IN EnumerationReference.EnumerationValues)) = SIZEOF(EnumerationValues)); END_ENTITY;