8.11.2.54 IfcMeasureValue（度量值）
8.11.2.54.1 语义定义（Semantic definition）
IFC 2x4 CHANGE 新增 IfcNonNegativeLengthMeasure。
8.11.2.54.2 类型值
8.11.2.54.3 形式化表示（Formal representation）
TYPE IfcMeasureValue = SELECT
(IfcAmountOfSubstanceMeasure
,IfcAreaMeasure
,IfcComplexNumber
,IfcContextDependentMeasure
,IfcCountMeasure
,IfcDescriptiveMeasure
,IfcElectricCurrentMeasure
,IfcLengthMeasure
,IfcLuminousIntensityMeasure
,IfcMassMeasure
,IfcNonNegativeLengthMeasure
,IfcNormalisedRatioMeasure
,IfcNumericMeasure
,IfcParameterValue
,IfcPlaneAngleMeasure
,IfcPositiveLengthMeasure
,IfcPositivePlaneAngleMeasure
,IfcPositiveRatioMeasure
,IfcRatioMeasure
,IfcSolidAngleMeasure
,IfcThermodynamicTemperatureMeasure
,IfcTimeMeasure
,IfcVolumeMeasure);
END_TYPE;