IfcQuantityTime是一个元素数量，它定义了一个时间度量，以提供与元素相关的时间属性。它通常由测量方法给出的特定测量规则下元素的配方信息给出。
示例：为墙浇注混凝土所需的时间量作为配方信息中人工部分的时间量给出。
IFC2x2中增加的新实体。
Formal Propositions
| Rule | Description |
|---|---|
| WR21 | If a unit is given, the unit type shall be time unit. |
| WR22 | A valid weight quantity shall be greater than or equal to zero. |
Attribute inheritance
| # | Attribute | Type | Cardinality | Description | C |
|---|---|---|---|---|---|
| IfcPhysicalQuantity | |||||
| 1 | Name | IfcLabel | [1:1] | Name of the element quantity or measure. The name attribute has to be made recognizable by further agreements. | X |
| 2 | Description | IfcText | [0:1] | Further explanation that might be given to the quantity. | X |
| HasExternalReferences | IfcExternalReferenceRelationship @RelatedResourceObjects |
S[0:?] | Reference to an external reference, e.g. library, classification, or document information, that is associated to the quantity. | X | |
| PartOfComplex | IfcPhysicalComplexQuantity @HasQuantities |
S[0:1] | Reference to a physical complex quantity in which the physical quantity may be contained. | X | |
| IfcPhysicalSimpleQuantity | |||||
| 3 | Unit | IfcNamedUnit | [0:1] | Optional assignment of a unit. If no unit is given, then the global unit assignment, as established at the IfcProject, applies to the quantity measures. | X |
| IfcQuantityTime | |||||
| 4 | TimeValue | IfcTimeMeasure | [1:1] | Time measure value of this quantity. | X |
| 5 | Formula | IfcLabel | [0:1] | A formula by which the quantity has been calculated. It can be assigned in addition to the actual value of the quantity. Formulas could be mathematic calculations (like width x height), database links, or a combination. The formula is for informational purposes only. | X |
EXPRESS Specification
ENTITY IfcQuantityTime
SUBTYPE OF (IfcPhysicalSimpleQuantity);
TimeValue : IfcTimeMeasure;
Formula : OPTIONAL IfcLabel;
WHERE
WR21 : NOT(EXISTS(SELFIfcPhysicalSimpleQuantity.Unit)) OR (SELFIfcPhysicalSimpleQuantity.Unit.UnitType = IfcUnitEnum.TIMEUNIT);
WR22 : TimeValue >= 0.;
END_ENTITY;