IfcSIUnit
实体定义
IfcSIUnit既包括米和秒等标准基本国际单位制，也包括帕斯卡、平方米和立方米等衍生国际单位制。
注：定义依据ISO/CD 10303-41:1992
国际单位制是用作标准的固定数量，根据ISO 1000（第2条）的定义，对项目进行测量。
注：对应的ISO 10303名称：si-unit，正式标准的最终定义请参考ISO/IS 10303-41。
IFC1.5.1中的新实体。
Attribute inheritance
| # | Attribute | Type | Cardinality | Description | C |
|---|---|---|---|---|---|
| IfcNamedUnit | |||||
| 2 | UnitType | IfcUnitEnum | [1:1] | The type of the unit. | X |
| IfcSIUnit | |||||
| 3 | Prefix | IfcSIPrefix | [0:1] | The SI Prefix for defining decimal multiples and submultiples of the unit. | X |
| 4 | Name | IfcSIUnitName | [1:1] | The word, or group of words, by which the SI unit is referred to.
NOTE Even though the SI system's base unit for mass is kilogram, the IfcSIUnit for mass is gram if no Prefix is asserted. |
X |
| Dimensions :=IfcDimensionsForSiUnit (SELF.Name) |
IfcDimensionalExponents | [1:1] | The dimensional exponents of SI units are derived by function IfcDimensionsForSiUnit. | X | |
EXPRESS Specification
ENTITY IfcSIUnit SUBTYPE OF (IfcNamedUnit); Prefix : OPTIONAL IfcSIPrefix; Name : IfcSIUnitName; DERIVE SELF\IfcNamedUnit.Dimensions : IfcDimensionalExponents := IfcDimensionsForSiUnit (SELF.Name); END_ENTITY;
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标签：Name,SI,IfcSIUnit,Prefix,ISO,unit From： https://www.cnblogs.com/herd/p/18108445