IfcMeasureResource(度量资源)
IfcMeasureResource可以分配给数量的单位和定义的度量值类型。
在不同类型的单位中，有五种基本情况：
①基本国际单位制单位，包括ISO-1000规定的主要物理量的一些基本单位，如米或毫米作为长度测量单位或平方米作为面积测量单位。该单位可能具有缩放前缀（例如：milli、kilo）。
②导出的国际单位，定义为基本国际单位的推导，例如牛顿（kg m/s2）作为力的单位。基本和导出的国际单位制都是用国际单位制表示的国际单位制。
③基于换算的单位，可通过比例因子从国际单位制中导出；例如英寸，可使用国际单位制定义长度测量，即英寸为25.4毫米。
④派生单位，可以定义为若干基本单位的派生或组合。在导出单位中，每个基本单位“分量”在定义导出单位时都具有维度指数；例如，kg/m2，其中kg（kg）具有维度指数1，m具有指数-2。
⑤上下文相关单位，不能定义为使用国际单位制的基于转换的单位。
关于在本规范中使用度量定义类型（例如，ifclengthemeasure、IfcTimeMeasure）作为属性数据类型，有三种基本情况：
Ⅰ、实体类型属性的数据类型是度量值定义的类型，因此在实例级别上不可能定义度量值的单位：
ENTITY IfcBoundingBox
SUBTYPE OF(IfcGeometricRepresentationItem);
Corner : IfcCartesianPoint;
XDim : IfcPositiveLengthMeasure;
YDim : IfcPositiveLengthMeasure;
ZDim : IfcPositiveLengthMeasure;
END_ENTITY;
在这种情况下，度量类型的相应单位的全局单位分配定义了此定义的度量类型的所有用法的单位（下面的情况2和3除外）。
Ⅱ、属性的数据类型是IfcMeasureWithUnit，它允许为该实体类型的每个实例定义单元，独立且可能重写全局单元分配：
ENTITY IfcConversionBasedUnit
SUPERTYPE OF (ONEOF
(IfcConversionBasedUnitWithOffset))
SUBTYPE OF (IfcNamedUnit);
Name : IfcLabel;
ConversionFactor : IfcMeasureWithUnit;
END_ENTITY;
在这种情况下，相关的度量定义类型（来自IfcMeasureWithUnit.ValueComponent:IfcValue select列表）不是由架构精确定义的，而是由上下文隐含的。
Ⅲ、实体类型有一个单独的“unit”属性，该属性允许为实体类型的另一个属性定义单位，以表示实际值：
ENTITY IfcPropertySingleValue
SUBTYPE OF (IfcSimpleProperty);
NominalValue : IfcValue;
Unit : OPTIONAL IfcUnit;
END_ENTITY;
尽管在不同实体类型的属性中，2和3种不同的单位可以用于同一实体类型的不同实例或同一度量值类型，但如果可以避免，建议不要为同一度量值定义的类型混合不同的单位。下面给出了上述每个基本情况的一些例子。
Measure Type Unit Symbol Derivation IfcSiUnitEnum IfcUnitEnum IfcDerivedUnitEnum Defined value types Absorbed dose, specific energy
impact, kerma, absorbed dose indexSI / Derived gray Gy J / kg GRAY ABSORBEDDOSEUNIT IfcAbsorbedDoseMeasure Acceleration Derived m / s2 ACCELERATIONUNIT IfcAccelerationMeasure Acidity (pH) Derived pH pH mol / l PHUNIT IfcPHMeasure Activity (of radionuclide) SI / Derived becquerel Bq 1 / s BECQUEREL RADIOACTIVITYUNIT IfcRadioActivityMeasure Amount of substance SI/Basic mole mol MOLE AMOUNTOFSUBSTANCEUNIT IfcAmountOfSubstanceMeasure Angular velocity Derived rad / s ANGULARVELOCITYUNIT IfcAngularVelocityMeasure Area SI/Derived square metre m2 m2 SQUARE_METRE AREAUNIT IfcAreaMeasure Area density Derived kg / m2 AREADENSITYUNIT IfcAreaDensityMeasure - IfcBoolean - IfcComplexNumber Compound plane angle Compound degree, min, s COMPOUNDPLANEANGLEUNIT IfcCompoundPlaneAngleMeasure - IfcContextDependentMeasure - IfcCountMeasure - IfcDescriptiveMeasure Capacitance SI / Derived farad F C / V FARAD ELECTRICCAPACITANCEUNIT IfcElectricCapacitanceMeasure Celsius temperature SI / Basic degree Celsius ºC 1 ºC = 1 K DEGREE_CELSIUS THERMODYNAMICTEMPERATUREUNIT IfcThermodynamicTemperatureMeasure Curvatue Derived rad / m CURVATUREUNIT IfcCurvatureMeasure - IfcDate
(lexical representation according to ISO 8601)- IfcDateTime
(lexical representation according to ISO 8601)Dose equivalent, dose equivalent
indexSI / Derived sievert Sv J / kg SIEVERT DOSEEQUIVALENTUNIT IfcDoseEquivalentMeasure - IfcDuration
(lexical representation according to ISO 8601)Dynamic viscosity Derived Pa · s DYNAMICVISCOSITYUNIT IfcDynamicViscosityMeasure Electric charge,
quantity of electricitySI / Derived coulomb C A · s COULOMB ELECTRICCHARGEUNIT IfcElectricChargeMeasure Electric conductance SI / Derived siemens S 1 / W SIEMENS ELECTRICCONDUCTANCEUNIT IfcElectricConductanceMeasure Electric current SI / Basic ampere A AMPERE ELECTRICCURRENTUNIT IfcElectricCurrentMeasure Electric potential, potential
difference, tension, electromotive forceSI / Derived volt V W / A VOLT ELECTRICVOLTAGEUNIT IfcElectricVoltageMeasure Electric resistance SI / Derived ohm W V / A OHM ELECTRICRESISTANCEUNIT IfcElectricResistanceMeasure Energy, work, quantity of heat SI / Derived joule J N · m JOULE ENERGYUNIT IfcEnergyMeasure Force SI / Derived newton N kg · m / s2 NEWTON FORCEUNIT IfcForceMeasure Frequency SI / Derived hertz Hz 1 / s HERTZ FREQUENCYUNIT IfcFrequencyMeasure Heat flux density Derived W / m2 HEATFLUXDENSITYUNIT IfcHeatFluxDensityMeasure Heating value Derived J / kg HEATINGVALUEUNIT IfcHeatingValueMeasure - IfcIdentifier Illuminance SI / Derived lux lx lm / m2 LUX ILLUMINANCEUNIT IfcIlluminanceMeasure Inductance SI / Derived henry H Wb / A HENRY INDUCTANCEUNIT IfcInductanceMeasure - IfcInteger (Integer) Count rate Derived 1 / s INTEGERCOUNTRATEUNIT IfcIntegerCountRateMeasure Ion concentration Derived g / l IONCONCENTRATIONUNIT IfcIonConcentrationMeasure Isothermal moisture capacity Derived m3 / kg ISOTHERMALMOISTURECAPACITYUNIT IfcIsothermalMoistureCapacityMeasure Kinematic viscosity Derived m2 / s KINEMATICVISCOSITYUNIT IfcKinematicViscosityMeasure Length SI / Basic metre m METRE LENGTHUNIT IfcLengthMeasure - IfcLabel Linear force Derived N / m LINEARFORCEUNIT IfcLinearForceMeasure Linear moment Derived N · m / m LINEARMOMENTUNIT IfcLinearMomentMeasure Linear stiffness Derived N / m LINEARSTIFFNESSUNIT IfcLinearStiffnessMeasure Linear velocity Derived m / s LINEARVELOCITYUNIT IfcLinearVelocityMeasure - IfcLogical Luminous flux SI / Derived lumen lm cd · sr LUMEN LUMINOUSFLUXUNIT IfcLuminousFluxMeasure Luminous intensity SI / Basic candela cd CANDELA LUMINOUSINTENSITYUNIT IfcLuminousIntensityMeasure Luminous intensity distribution Derived cd / lm LUMINOUSINTENSITYDISTRIBUTIONUNIT IfcLuminousIntensityDistributionMeasure Magnetic flux SI / Derived weber Wb V · s WEBER MAGNETICFLUXUNIT IfcMagneticFluxMeasure Magnetic flux density SI / Derived tesla T Wb / m2 TESLA MAGNETICFLUXDENSITYUNIT IfcMagneticFluxDensityMeasure Mass SI / Basic gram g (kg) GRAM MASSUNIT IfcMassMeasure Mass density Derived kg / m3 MASSDENSITYUNIT IfcMassDensityMeasure Mass flow rate Derived kg / s MASSFLOWRATEUNIT IfcMassFlowRateMeasure Mass per length Derived kg / m MASSPERLENGTHUNIT IfcMassPerLengthMeasure Modulus of elasticity Derived N / m2 MODULUSOFELASTICITYUNIT IfcModulusOfElasticityMeasure Modulus of linear subgrade reaction Derived N / m2 MODULUSOFLINEARSUBGRADEREACTIONUNIT IfcModulusOfLinearSubgradeReactionMeasure Modulus of rotational subgrade reaction Derived N · m / m · rad MODULUSOFROTATIONALSUBGRADEREACTIONUNIT IfcModulusOfRotationalSubgradeReactionMeasure Modulus of subgrade reaction Derived N / m3 MODULUSOFSUBGRADEREACTIONUNIT IfcModulusOfSubgradeReactionMeasure Moisture diffusivity Derived m3 / s MOISTUREDIFFUSIVITYUNIT IfcMoistureDiffusivityMeasure Molecular weight Derived g / mol MOLECULARWEIGHTUNIT IfcMolecularWeightMeasure Moment of inertia Derived m4 MOMENTOFINERTIAUNIT IfcMomentOfInertiaMeasure - IfcMonetaryMeasure (Non negative length) m LENGTHUNIT IfcNonNegativeLengthMeasure - IfcNormalisedRatioMeasure - IfcNumericMeasure - IfcParameterValue Planar force Derived N / m2 PLANARFORCEUNIT IfcPlanarForceMeasure Plane angle SI / Derived radian rad m / m = 1 RADIAN PLANEANGLEUNIT IfcPlaneAngleMeasure (Positive length) m LENGTHUNIT IfcPositiveLengthMeasure (Positive plane angle) rad PLANEANGLEUNIT IfcPositivePlaneAngleMeasure - IfcPositiveRatioMeasure Power SI / Derived watt W J / s WATT POWERUNIT IfcPowerMeasure Pressure, stress SI / Derived pascal Pa N / m2 PASCAL PRESSUREUNIT IfcPressureMeasure - IfcRatioMeasure - IfcReal Rotational frequency Derived cycles / s ROTATIONALFREQUENCYUNIT IfcRotationalFrequencyMeasure Rotational mass Derived kg · m2 ROTATIONALMASSUNIT IfcRotationalMassMeasure Rotational stiffness Derived N · m / rad ROTATIONALSTIFFNESSUNIT IfcRotationalStiffnessMeasure Sectional area integral Derived m5 SECTIONALAREAINTEGRALUNIT IfcSectionalAreaIntegralMeasure Section modulus Derived m3 SECTIONMODULUSUNIT IfcSectionModulusMeasure Shear modulus Derived N / m2 SHEARMODULUSUNIT IfcShearModulusMeasure Solid angle SI / Derived steradin sr m2 / m2 = 1 STERADIAN SOLIDANGLEUNIT IfcSolidAngleMeasure Sound power watt W W SOUNDPOWERUNIT IfcSoundPowerMeasure Sound power level decibel db W / W SOUNDPOWERLEVELUNIT IfcSoundPowerLevelMeasure Sound pressure pascal Pa Pa SOUNDPRESSUREUNIT IfcSoundPressureMeasure Sound pressure level decibel db Pa / Pa SOUNDPRESSURELEVELUNIT IfcSoundPressureLevelMeasure Specific heat capacity Derived J / kg· K SPECIFICHEATCAPACITYUNIT IfcSpecificHeatCapacityMeasure Temperature gradient K / m TEMPERATUREGRADIENTUNIT IfcTemperatureGradientMeasure Temperature change K / s TEMPERATURERATEOFCHANGEUNIT IfcTemperatureRateOfChangeMeasure - IfcText Thermal admittance Derived W / m2 · K THERMALADMITTANCEUNIT IfcThermalAdmittanceMeasure Thermal conductivity Derived W / m · K THERMALCONDUCTIVITYUNIT IfcThermalConductivityMeasure Thermal expansion coefficient 1 / K THERMALEXPANSIONCOEFFICIENTUNIT IfcThermalExpansionCoefficientMeasure Thermal resistance Derived m2 · K / W THERMALRESISTANCEUNIT IfcThermalResistanceMeasure Thermal transmittance Derived W / m2 · K THERMALTRANSMITTANCEUNIT IfcThermalTransmittanceMeasure Thermodynamic temperature SI / Basic kelvin K KELVIN THERMODYNAMICTEMPERATUREUNIT IfcThermodynamicTemperatureMeasure - IfcTime
(lexical representation according to ISO 8601)Time SI / Basic second s SECOND TIMEUNIT IfcTimeMeasure - IfcTimeStamp Torque Derived N· m TORQUEUNIT IfcTorqueMeasure Vapor permeability Derived kg / s · m · Pa VAPORPERMEABILITYUNIT IfcVaporPermeabilityMeasure Volume SI / Derived cubic metre m3 m3 CUBIC_METRE VOLUMEUNIT IfcVolumeMeasure Volumetric flow rate Derived m3 / s VOLUMETRICFLOWRATEUNIT IfcVolumetricFlowRateMeasure Warping constant m6 WARPINGCONSTANTUNIT IfcWarpingConstantMeasure Warping moment Derived N · m2 WARPINGMOMENTUNIT IfcWarpingMomentMeasure
Types
1 IfcAbsorbedDoseMeasure
2 IfcAccelerationMeasure
3 IfcAmountOfSubstanceMeasure
4 IfcAngularVelocityMeasure
5 IfcAreaDensityMeasure
6 IfcAreaMeasure
7 IfcBinary
8 IfcBoolean
9 IfcComplexNumber
10 IfcCompoundPlaneAngleMeasure
11 IfcContextDependentMeasure
12 IfcCountMeasure
13 IfcCurvatureMeasure
14 IfcDescriptiveMeasure
15 IfcDoseEquivalentMeasure
16 IfcDynamicViscosityMeasure
17 IfcElectricCapacitanceMeasure
18 IfcElectricChargeMeasure
19 IfcElectricConductanceMeasure
20 IfcElectricCurrentMeasure
21 IfcElectricResistanceMeasure
22 IfcElectricVoltageMeasure
23 IfcEnergyMeasure
24 IfcForceMeasure
25 IfcFrequencyMeasure
26 IfcHeatFluxDensityMeasure
27 IfcHeatingValueMeasure
28 IfcIdentifier
29 IfcIlluminanceMeasure
30 IfcInductanceMeasure
31 IfcInteger
32 IfcIntegerCountRateMeasure
33 IfcIonConcentrationMeasure
34 IfcIsothermalMoistureCapacityMeasure
35 IfcKinematicViscosityMeasure
36 IfcLabel
37 IfcLengthMeasure
38 IfcLinearForceMeasure
39 IfcLinearMomentMeasure
40 IfcLinearStiffnessMeasure
41 IfcLinearVelocityMeasure
42 IfcLogical
43 IfcLuminousFluxMeasure
44 IfcLuminousIntensityDistributionMeasure
45 IfcLuminousIntensityMeasure
46 IfcMagneticFluxDensityMeasure
47 IfcMagneticFluxMeasure
48 IfcMassDensityMeasure
49 IfcMassFlowRateMeasure
50 IfcMassMeasure
51 IfcMassPerLengthMeasure
52 IfcModulusOfElasticityMeasure
53 IfcModulusOfLinearSubgradeReactionMeasure
54 IfcModulusOfRotationalSubgradeReactionMeasure
55 IfcModulusOfSubgradeReactionMeasure
56 IfcMoistureDiffusivityMeasure
57 IfcMolecularWeightMeasure
58 IfcMomentOfInertiaMeasure
59 IfcMonetaryMeasure
60 IfcNonNegativeLengthMeasure
61 IfcNormalisedRatioMeasure
62 IfcNumericMeasure
63 IfcParameterValue
64 IfcPHMeasure
65 IfcPlanarForceMeasure
66 IfcPlaneAngleMeasure
67 IfcPositiveInteger
68 IfcPositiveLengthMeasure
69 IfcPositivePlaneAngleMeasure
70 IfcPositiveRatioMeasure
71 IfcPowerMeasure
72 IfcPressureMeasure
73 IfcRadioActivityMeasure
74 IfcRatioMeasure
75 IfcReal
76 IfcRotationalFrequencyMeasure
77 IfcRotationalMassMeasure
78 IfcRotationalStiffnessMeasure
79 IfcSectionalAreaIntegralMeasure
80 IfcSectionModulusMeasure
81 IfcShearModulusMeasure
82 IfcSolidAngleMeasure
83 IfcSoundPowerLevelMeasure
84 IfcSoundPowerMeasure
85 IfcSoundPressureLevelMeasure
86 IfcSoundPressureMeasure
87 IfcSpecificHeatCapacityMeasure
88 IfcTemperatureGradientMeasure
89 IfcTemperatureRateOfChangeMeasure
90 IfcText
91 IfcThermalAdmittanceMeasure
92 IfcThermalConductivityMeasure
93 IfcThermalExpansionCoefficientMeasure
94 IfcThermalResistanceMeasure
95 IfcThermalTransmittanceMeasure
96 IfcThermodynamicTemperatureMeasure
97 IfcTimeMeasure
98 IfcTorqueMeasure
99 IfcVaporPermeabilityMeasure
100 IfcVolumeMeasure
101 IfcVolumetricFlowRateMeasure
102 IfcWarpingConstantMeasure
103 IfcWarpingMomentMeasure
104 IfcDerivedUnitEnum
105 IfcSIPrefix
106 IfcSIUnitName
107 IfcUnitEnum
108 IfcDerivedMeasureValue
109 IfcMeasureValue
110 IfcSimpleValue
111 IfcUnit
112 IfcValue
Entities
1 IfcContextDependentUnit
2 IfcConversionBasedUnit
3 IfcConversionBasedUnitWithOffset
4 IfcDerivedUnit
5 IfcDerivedUnitElement
6 IfcDimensionalExponents
7 IfcMeasureWithUnit
8 IfcMonetaryUnit
9 IfcNamedUnit
10 IfcSIUnit
11 IfcUnitAssignment
Functions
1 IfcCorrectDimensions
2 IfcCorrectUnitAssignment
3 IfcDeriveDimensionalExponents
4 IfcDimensionsForSiUnit
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类型：
1 IfcAbsorbedDoseMeasure ()
2 IfcAccelerationMeasure (加速度单位)
3 IfcAmountOfSubstanceMeasure ()
4 IfcAngularVelocityMeasure (角速度单位)
5 IfcAreaDensityMeasure (面积密度单位)
6 IfcAreaMeasure (面积单位)
7 IfcBinary ()
8 IfcBoolean (布尔型)
9 IfcComplexNumber (复数)
10 IfcCompoundPlaneAngleMeasure (复合平面角单位)
11 IfcContextDependentMeasure
12 IfcCountMeasure (计数单位)
13 IfcCurvatureMeasure (曲率单位)
14 IfcDescriptiveMeasure
15 IfcDoseEquivalentMeasure
16 IfcDynamicViscosityMeasure (动态粘度单位)
17 IfcElectricCapacitanceMeasure (电容单位)
18 IfcElectricChargeMeasure (电荷单位)
19 IfcElectricConductanceMeasure (电导单位)
20 IfcElectricCurrentMeasure (电流单位)
21 IfcElectricResistanceMeasure
22 IfcElectricVoltageMeasure
23 IfcEnergyMeasure
24 IfcForceMeasure
25 IfcFrequencyMeasure
26 IfcHeatFluxDensityMeasure
27 IfcHeatingValueMeasure
28 IfcIdentifier
29 IfcIlluminanceMeasure
30 IfcInductanceMeasure
31 IfcInteger
32 IfcIntegerCountRateMeasure
33 IfcIonConcentrationMeasure
34 IfcIsothermalMoistureCapacityMeasure
35 IfcKinematicViscosityMeasure
36 IfcLabel
37 IfcLengthMeasure
38 IfcLinearForceMeasure
39 IfcLinearMomentMeasure
40 IfcLinearStiffnessMeasure
41 IfcLinearVelocityMeasure
42 IfcLogical
43 IfcLuminousFluxMeasure
44 IfcLuminousIntensityDistributionMeasure
45 IfcLuminousIntensityMeasure
46 IfcMagneticFluxDensityMeasure
47 IfcMagneticFluxMeasure
48 IfcMassDensityMeasure
49 IfcMassFlowRateMeasure
50 IfcMassMeasure
51 IfcMassPerLengthMeasure
52 IfcModulusOfElasticityMeasure
53 IfcModulusOfLinearSubgradeReactionMeasure
54 IfcModulusOfRotationalSubgradeReactionMeasure
55 IfcModulusOfSubgradeReactionMeasure
56 IfcMoistureDiffusivityMeasure
57 IfcMolecularWeightMeasure
58 IfcMomentOfInertiaMeasure
59 IfcMonetaryMeasure
60 IfcNonNegativeLengthMeasure
61 IfcNormalisedRatioMeasure
62 IfcNumericMeasure
63 IfcParameterValue
64 IfcPHMeasure
65 IfcPlanarForceMeasure
66 IfcPlaneAngleMeasure
67 IfcPositiveInteger
68 IfcPositiveLengthMeasure
69 IfcPositivePlaneAngleMeasure
70 IfcPositiveRatioMeasure
71 IfcPowerMeasure
72 IfcPressureMeasure
73 IfcRadioActivityMeasure
74 IfcRatioMeasure
75 IfcReal
76 IfcRotationalFrequencyMeasure
77 IfcRotationalMassMeasure
78 IfcRotationalStiffnessMeasure
79 IfcSectionalAreaIntegralMeasure
80 IfcSectionModulusMeasure
81 IfcShearModulusMeasure
82 IfcSolidAngleMeasure
83 IfcSoundPowerLevelMeasure
84 IfcSoundPowerMeasure
85 IfcSoundPressureLevelMeasure
86 IfcSoundPressureMeasure
87 IfcSpecificHeatCapacityMeasure
88 IfcTemperatureGradientMeasure
89 IfcTemperatureRateOfChangeMeasure
90 IfcText
91 IfcThermalAdmittanceMeasure
92 IfcThermalConductivityMeasure
93 IfcThermalExpansionCoefficientMeasure
94 IfcThermalResistanceMeasure
95 IfcThermalTransmittanceMeasure
96 IfcThermodynamicTemperatureMeasure
97 IfcTimeMeasure
98 IfcTorqueMeasure
99 IfcVaporPermeabilityMeasure
100 IfcVolumeMeasure
101 IfcVolumetricFlowRateMeasure
102 IfcWarpingConstantMeasure
103 IfcWarpingMomentMeasure
104 IfcDerivedUnitEnum
105 IfcSIPrefix
106 IfcSIUnitName
107 IfcUnitEnum
108 IfcDerivedMeasureValue
109 IfcMeasureValue
110 IfcSimpleValue
111 IfcUnit
112 IfcValue
实体：
1 IfcContextDependentUnit
2 IfcConversionBasedUnit
3 IfcConversionBasedUnitWithOffset
4 IfcDerivedUnit
5 IfcDerivedUnitElement
6 IfcDimensionalExponents
7 IfcMeasureWithUnit
8 IfcMonetaryUnit
9 IfcNamedUnit
10 IfcSIUnit
11 IfcUnitAssignment
函数：
1 IfcCorrectDimensions
2 IfcCorrectUnitAssignment
3 IfcDeriveDimensionalExponents
4 IfcDimensionsForSiUnit (国际单位制尺寸)