4.1.6.3 Quantity Sets
任何对象的专门化都可以与多个数量集实例相关联。一个数量集包含多个数量实例。数量实例值的类型是计数、长度、面积、体积、重量、时间，或数量的组合。每个数量由其名称、值以及可选的描述和公式定义。
数量集通过 IfcElementQuantity Name 属性确定了数量集的通用标识符。本规范包含一些预定义数量集，每个数量集都提供了模板定义。模板的名称必须用作 Name 属性的值。MethodOfMeasurement 属性指定了计算各个数量值的方法。对于本规范中包含的数量集模板，MethodOfMeasurement 的值应为“BaseQuantities”。
下图展示了应用此概念时使用的通用类和关系。
此外，概念可能对常见或标准化的行业实践和场景具有特殊意义。对于这些特定的使用场景，下表展示了用户可采用的推荐通用使用模式列表。
G
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcObject.htm'>IfcObject</a>
IfcObject 1. GlobalId
[1:1]
2. OwnerHistory
[0:1]
3. Name
[0:1]
4. Description
[0:1]
HasAssignments
[0:?]
Nests
[0:1]
IsNestedBy
[0:?]
HasContext
[0:1]
IsDecomposedBy
[0:?]
Decomposes
[0:1]
HasAssociations
[0:?]
5. ObjectType
[0:1]
IsDeclaredBy
[0:1]
Declares
[0:?]
IsTypedBy
[0:1]
IsDefinedBy
[0:?]
...
PredefinedType
PredefinedType
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcRelDefinesByProperties.htm'>IfcRelDefinesByProperties</a>
IfcRelDefinesByProperties 1. GlobalId
[1:1]
2. OwnerHistory
[0:1]
3. Name
[0:1]
4. Description
[0:1]
5. RelatedObjects
[1:?]
6. RelatingPropertyDefinition
[1:1]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcObject.htm'>IfcObject</a>:IsDefinedBy1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcRelDefinesByProperties.htm'>IfcRelDefinesByProperties</a>:RelatedObjects0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>
IfcElementQuantity 1. GlobalId
[1:1]
2. OwnerHistory
[0:1]
QsetName
3. Name
[0:1]
4. Description
[0:1]
HasContext
[0:1]
HasAssociations
[0:?]
DefinesType
[0:?]
IsDefinedBy
[0:?]
DefinesOccurrence
[0:?]
5. MethodOfMeasurement
[0:1]
Quantities
6. Quantities
[1:?]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcRelDefinesByProperties.htm'>IfcRelDefinesByProperties</a>:RelatingPropertyDefinition1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:IfcElementQuantity0
IfcLabel_0
IfcLabel
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:Name1->IfcLabel_0:IfcLabel0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcText.htm'>IfcText</a>
IfcText
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:Description1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcText.htm'>IfcText</a>:IfcText0
IfcLabel_1
IfcLabel
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:MethodOfMeasurement1->IfcLabel_1:IfcLabel0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityLength.htm'>IfcQuantityLength</a>
IfcQuantityLength 1. Name
[1:1]
2. Description
[0:1]
HasExternalReferences
[0:?]
PartOfComplex
[0:1]
3. Unit
[0:1]
4. LengthValue
[1:1]
5. Formula
[0:1]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:Quantities1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityLength.htm'>IfcQuantityLength</a>:IfcQuantityLength0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityArea.htm'>IfcQuantityArea</a>
IfcQuantityArea 1. Name
[1:1]
2. Description
[0:1]
HasExternalReferences
[0:?]
PartOfComplex
[0:1]
3. Unit
[0:1]
4. AreaValue
[1:1]
5. Formula
[0:1]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:Quantities1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityArea.htm'>IfcQuantityArea</a>:IfcQuantityArea0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityVolume.htm'>IfcQuantityVolume</a>
IfcQuantityVolume 1. Name
[1:1]
2. Description
[0:1]
HasExternalReferences
[0:?]
PartOfComplex
[0:1]
3. Unit
[0:1]
4. VolumeValue
[1:1]
5. Formula
[0:1]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:Quantities1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityVolume.htm'>IfcQuantityVolume</a>:IfcQuantityVolume0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityWeight.htm'>IfcQuantityWeight</a>
IfcQuantityWeight 1. Name
[1:1]
2. Description
[0:1]
HasExternalReferences
[0:?]
PartOfComplex
[0:1]
3. Unit
[0:1]
4. WeightValue
[1:1]
5. Formula
[0:1]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:Quantities1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityWeight.htm'>IfcQuantityWeight</a>:IfcQuantityWeight0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityCount.htm'>IfcQuantityCount</a>
IfcQuantityCount 1. Name
[1:1]
2. Description
[0:1]
HasExternalReferences
[0:?]
PartOfComplex
[0:1]
3. Unit
[0:1]
4. CountValue
[1:1]
5. Formula
[0:1]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:Quantities1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityCount.htm'>IfcQuantityCount</a>:IfcQuantityCount0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityTime.htm'>IfcQuantityTime</a>
IfcQuantityTime 1. Name
[1:1]
2. Description
[0:1]
HasExternalReferences
[0:?]
PartOfComplex
[0:1]
3. Unit
[0:1]
4. TimeValue
[1:1]
5. Formula
[0:1]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcElementQuantity.htm'>IfcElementQuantity</a>:Quantities1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityTime.htm'>IfcQuantityTime</a>:IfcQuantityTime0
Length_Quantity
Length Quantity
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityLength.htm'>IfcQuantityLength</a>->Length_Quantity
Area_Quantity
Area Quantity
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityArea.htm'>IfcQuantityArea</a>->Area_Quantity
Volume_Quantity
Volume Quantity
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityVolume.htm'>IfcQuantityVolume</a>->Volume_Quantity
Weight_Quantity
Weight Quantity
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityWeight.htm'>IfcQuantityWeight</a>->Weight_Quantity
Count_Quantity
Count Quantity
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityCount.htm'>IfcQuantityCount</a>->Count_Quantity
Time_Quantity
Time Quantity
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcQuantityTime.htm'>IfcQuantityTime</a>->Time_Quantity
Figure 4.1.6.3.A 表 4.1.6.3.B