IfcDerivedUnit
实体定义
注：定义依据ISO/CD 10303-41:1992
派生单位是单位的表达式。
示例牛顿每平方毫米是一个推导单位。
注：对应的ISO 10303名称：derived_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 |
|---|---|---|---|---|---|
| IfcDerivedUnit | |||||
| 1 | Elements | IfcDerivedUnitElement | S[1:?] | The group of units and their exponents that define the derived unit. | X |
| 2 | UnitType | IfcDerivedUnitEnum | [1:1] | Name of the derived unit chosen from an enumeration of derived unit types for use in IFC models. | X |
| 3 | UserDefinedType | IfcLabel | [0:1] | X | |
| Dimensions :=IfcDeriveDimensionalExponents(Elements) |
IfcDimensionalExponents | [1:1] | Dimensional exponents derived using the function IfcDerivedDimensionalExponents using (SELF) as the input value. | X | |
EXPRESS Specification
ENTITY IfcDerivedUnit; Elements : SET [1:?] OF IfcDerivedUnitElement; UnitType : IfcDerivedUnitEnum; UserDefinedType : OPTIONAL IfcLabel; DERIVE Dimensions : IfcDimensionalExponents := IfcDeriveDimensionalExponents(Elements); WHERE WR1 : (SIZEOF (Elements) > 1) OR ((SIZEOF (Elements) = 1) AND (Elements[1].Exponent <> 1 )); WR2 : (UnitType <> IfcDerivedUnitEnum.USERDEFINED) OR ((UnitType = IfcDerivedUnitEnum.USERDEFINED) AND (EXISTS(SELF.UserDefinedType))); END_ENTITY;
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标签：Elements,IfcDerivedUnit,derived,IfcDerivedUnitEnum,UnitType,unit From： https://www.cnblogs.com/herd/p/18108414