Property

Every property in IFC has a data type and name and can have a definition explaining its meaning and a quantity kind defining a measure and a unit of storage.

Data types

Every property in IFC has a data type. Allowed IFC data types are:

String,
Integer,
Real (double precision number),
Boolean (true/false),
Binary,
List (multiple values of the same data type).
TODO List or Array? It could be an unknown size.
TODO logical (true/false/unknown)?
TODO what about empty values?

Units and quantity kinds

The quantity kinds are useful to help interpret the property value and enable software to make automatic unit conversions.

All the data in IFC is stored using the default units for every quantity kind, such as metres for length. That helps to ensure consistency, precision, performance and interoperability across implementations. Software can display user-prefered units (read more: display units).

Measureless units

Many numeric properties require units that are not related to any defined quantity kind. In those cases, a basic data type Real/Integer should be used, with the unit specified in the property definition.

For example:

monetary units, like the euro (€/EUR) and US dollar ($/USD), depend on dynamic currency exchange rates, therefore in IFC should be treated as real numbers without a measure.
pixel (px), a unit of digital image resolution, has no physical size unless a resolution is specified, and in IFC should be treated as an integer, not a measurable length.
kilobyte (kB), a unit of digital information storage equal to 1,024 binary bytes, in IFC should be treated as an integer.

Derived units

Most common derived units are already included in the table. For example, "cubic metre per second" is derived from time and volume, which is derived from length.

For all the missing derived units, we recommend following the same approach as with measureless units. If there are important quantity kinds missing you can suggest an improvement here: IFC5 suggestions.

Special units

Some properties require special units that are based on those defined in the table but with additional meaning. That semantic meaning should be conveyed through property definition, and a basic quantity kind should be applied to allow for conversions. For example:

the unit of global warming potential, "kilogram CO₂ equivalent" (kg CO₂ eq), should be defined as a mass quantity kind and stored in kilograms, with the meaning clarified in the definition.
"millimetre of mercury" (mmHg), despite the name suggesting it is a length quantity, should be represented as a pressure quantity in Pascals (1 mmHg = 133.322 Pa).

Display units

Software can display IFC data in user-prefered units. The software needs to perform the conversion. The IFC does not specify the conversion factors or tolerance. The conversion typically involves:

scaling (e.g. kilo = x1000, mili = x0.001)
converting between metric and imperial systems (e.g. inch ➝ metre = x0.0254, pound ➝ kilogram = x2.2046226218)
switching between units that are more applicable to context (e.g. litre ➝ cubic meters = *0.001, degree ➝ radians = π/180)

List of IFC quantity kinds

DECIDE: add measure for information? kilobyte? or SI unit for information - bit (8 bytes)? This would enable conversions kB, GB, TB...

Original name	Name	QUDT quantity kind	Data Type	Unit name	Unit symbol	QUDT unit	Dimensional exponents	IFC4.3 unit enumeration	IFC Base unit?	SI Base or derived unit?	InIFC2x3	InIFC4	InIFC4.3	InIFC5	Tier	Comment
IFCPLANEANGLEMEASURE	Plane angle	Angle	Real	Degrees	°	DEG		IFCUnitEnum.PLANEANGLEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	1	Changed from radians to degrees. DECIDE rad or degrees.
IFCTHERMODYNAMICTEMPERATUREMEASURE	Thermodynamic temperature	Temperature	Real	Kelvin	°K	K	(0, 0, 0, 0, 1, 0, 0)	IFCUnitEnum.THERMODYNAMICTEMPERATUREUNIT	✔️	✔️ (base)	✔️	✔️	✔️	✔️	1	DECIDE kelvin or celcius (DEG_C). DECIDE Temperature or Thermodynamic Temperature
IFCELECTRICCURRENTMEASURE	Electric current	ElectricCurrent	Real	Ampere	A	A	(0, 0, 0, 1, 0, 0, 0)	IFCUnitEnum.ELECTRICCURRENTUNIT	✔️	✔️ (base)	✔️	✔️	✔️	✔️	1
IFCTIMEMEASURE	Time	Time	Real	Second	s	SEC	(0, 0, 1, 0, 0, 0, 0)	IFCUnitEnum.TIMEUNIT	✔️	✔️ (base)	✔️	✔️	✔️	✔️	1
IFCFREQUENCYMEASURE	Frequency	Frequency	Real	Hertz	Hz	HZ	(0, 0, -1, 0, 0, 0, 0)	IFCUnitEnum.FREQUENCYUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	1
IFCMASSMEASURE	Mass	Mass	Real	Kilogram	Kg	KiloGM	(0, 1, 0, 0, 0, 0, 0)	IFCUnitEnum.MASSUNIT	✔️	✔️ (base)	✔️	✔️	✔️	✔️	1
IFCLENGTHMEASURE	Length	Length	Real	Metre	m	M	(1, 0, 0, 0, 0, 0, 0)	IFCUnitEnum.LENGTHUNIT	✔️	✔️ (base)	✔️	✔️	✔️	✔️	1
IFCLINEARVELOCITYMEASURE	Linear velocity	Velocity	Real	Metre per second	m / s	M-PER-SEC	(1, 0, -1, 0, 0, 0, 0)	IFCDerivedUnitEnum.LINEARVELOCITYUNIT	❌	❌	✔️	✔️	✔️	✔️	1	DECIDE Speed or Linear velocity
IFCFORCEMEASURE	Force	Force	Real	Newton	N	N	(1, 1, -2, 0, 0, 0, 0)	IFCUnitEnum.FORCEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	1
IFCPRESSUREMEASURE	Pressure	Pressure	Real	Pascal	Pa	PA	(-1, 1, -2, 0, 0, 0, 0)	IFCUnitEnum.PRESSUREUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	1	=N/m² = J/m³
IFCAREAMEASURE	Area	Area	Real	Square metre	m²	M2	(2, 0, 0, 0, 0, 0, 0)	IFCUnitEnum.AREAUNIT	✔️	❌	✔️	✔️	✔️	✔️	1
IFCENERGYMEASURE	Energy	Energy	Real	Joule	J	J	(2, 1, -2, 0, 0, 0, 0)	IFCUnitEnum.ENERGYUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	1
IFCPOWERMEASURE	Power	Power	Real	Watt	W	W	(2, 1, -3, 0, 0, 0, 0)	IFCUnitEnum.POWERUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	1
IFCVOLUMEMEASURE	Volume	Volume	Real	Cubic metre	m³	M3	(3, 0, 0, 0, 0, 0, 0)	IFCUnitEnum.VOLUMEUNIT	✔️	❌	✔️	✔️	✔️	✔️	1
IFCPHMEASURE	Acidity	Acidity	Real	pH	pH	PH		IFCDerivedUnitEnum.PHUNIT	❌	❌	✔️	✔️	✔️	✔️	2	Changed name from PH to Acidity DECIDE
IFCLUMINOUSINTENSITYMEASURE	Luminous intensity	LuminousIntensity	Real	Candela	cd	CD	(0, 0, 0, 0, 0, 0, 1)	IFCUnitEnum.LUMINOUSINTENSITYUNIT	✔️	✔️ (base)	✔️	✔️	✔️	✔️	2
IFCLUMINOUSFLUXMEASURE	Luminous flux	LuminousFlux	Real	Lumen	lm	LM	(0, 0, 0, 0, 0, 0, 1)	IFCUnitEnum.LUMINOUSFLUXUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	2
IFCAMOUNTOFSUBSTANCEMEASURE	Amount of substance	AmountOfSubstance	Real	Mole	mol	MOL	(0, 0, 0, 0, 0, 1, 0)	IFCUnitEnum.AMOUNTOFSUBSTANCEUNIT	✔️	✔️ (base)	✔️	✔️	✔️	✔️	2
IFCILLUMINANCEMEASURE	Illuminance	Illuminance	Real	Lux	lx	LUX	(-2, 0, 0, 0, 0, 0, 1)	IFCUnitEnum.ILLUMINANCEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	2	=lm/m²
IFCELECTRICVOLTAGEMEASURE	Electric voltage	Voltage	Real	Volt	V	V	(2, 1, -3, -1, 0, 0, 0)	IFCUnitEnum.ELECTRICVOLTAGEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	2	DECIDE QUDT has different name
IFCELECTRICRESISTANCEMEASURE	Electric resistance	Resistance	Real	Ohm	Ω	OHM	(2, 1, -3, -2, 0, 0, 0)	IFCUnitEnum.ELECTRICRESISTANCEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	2	DECIDE QUDT has different name. Other name: Impedance
IFCSOLIDANGLEMEASURE	Solid angle	SolidAngle	Real	Steradin	sr	SR		IFCUnitEnum.SOLIDANGLEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	3
IFCRADIOACTIVITYMEASURE	Radio activity	Radioactivity	Real	Becquerel	Bq	BQ	(0, 0, -1, 0, 0, 0, 0)	IFCUnitEnum.RADIOACTIVITYUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	3
IFCELECTRICCHARGEMEASURE	Electric charge	ElectricCharge	Real	Coulomb	C	C	(0, 0, 1, 1, 0, 0, 0)	IFCUnitEnum.ELECTRICCHARGEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	3
IFCMAGNETICFLUXDENSITYMEASURE	Magnetic flux density	MagneticFluxDensity	Real	Square metre kelvin per watt	T	T	(0, 1, -2, -1, 0, 0, 0)	IFCUnitEnum.MAGNETICFLUXDENSITYUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	3	=Wb / m2
IFCABSORBEDDOSEMEASURE	Absorbed dose	AbsorbedDose	Real	Gray	Gy	GY	(2, 0, -2, 0, 0, 0, 0)	IFCUnitEnum.ABSORBEDDOSEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	3	=J/kg =m²⋅s⁻²
IFCDOSEEQUIVALENTMEASURE	Dose equivalent	DoseEquivalent	Real	Sievert	Sv	SV	(2, 0, -2, 0, 0, 0, 0)	IFCUnitEnum.DOSEEQUIVALENTUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	3	=J/kg =m²⋅s⁻²
IFCMAGNETICFLUXMEASURE	Magnetic flux	MagneticFlux	Real	Weber	Wb	WB	(2, 1, -2, -1, 0, 0, 0)	IFCDerivedUnitEnum.MAGNETICFLUXUNIT	❌	✔️ (derived)	✔️	✔️	✔️	✔️	3
IFCINDUCTANCEMEASURE	Inductance	Inductance	Real	Henry	H	H	(2, 1, -2, -2, 0, 0, 0)	IFCUnitEnum.INDUCTANCEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	3	=Wb / A
IFCELECTRICCONDUCTANCEMEASURE	Electric conductance	ElectricConductance	Real	Siemens	S	S	(-2, -1, 3, 2, 0, 0, 0)	IFCUnitEnum.ELECTRICCONDUCTANCEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	3	=Ω^-1
IFCELECTRICCAPACITANCEMEASURE	Electric capacitance	ElectricCapacitance	Real	Farad	F	F	(-2, 1, 4, 1, 0, 0, 0)	IFCUnitEnum.ELECTRICCAPACITANCEUNIT	✔️	✔️ (derived)	✔️	✔️	✔️	✔️	3
IFCMASSDENSITYMEASURE	Mass density	MassDensity	Real	Kilogram per cubic metre	Kg / m³	KiloGM-PER-M3	(-3, 1, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.MASSDENSITYUNIT	❌	❌	✔️	✔️	✔️	❔	2	DECIDE rename to "Density"
IFCACCELERATIONMEASURE	Acceleration	Acceleration	Real	Metre per second squared	m / s²	M-PER-SEC2	(1, 0, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.ACCELERATIONUNIT	❌	❌	✔️	✔️	✔️	❔	2
IFCTHERMALRESISTANCEMEASURE	Thermal resistance	ThermalResistance	Real	Square metre kelvin per watt	m² K / W	M2-K-PER-W	(0, -1, 3, 0, 1, 0, 0)	IFCDerivedUnitEnum.THERMALRESISTANCEUNIT	❌	❌	✔️	✔️	✔️	❔	2
IFCSECTIONMODULUSMEASURE	Section modulus	SectionModulus	Real	Cubic metre	m³	M3	(3, 0, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.SECTIONMODULUSUNIT	❌	❌	✔️	✔️	✔️	❔	2
IFCMOMENTOFINERTIAMEASURE	Moment of inertia	SecondAxialMomentOfArea	Real	Quartic metre	m⁴		(4, 0, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.MOMENTOFINERTIAUNIT	❌	❌	✔️	✔️	✔️	❔	2	TODO this is wrong in IFC - Moment of inertia is in kg⋅m2 and not in m4. This is probably confused with SecondAxialMomentOfArea
IFCLINEARFORCEMEASURE	Linear force	ForcePerLength	Real	Newton per metre	N / m	N-PER-M	(0, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.LINEARFORCEUNIT	❌	❌	✔️	✔️	✔️	❔	2	DECIDE QUDT has different name
IFCLINEARMOMENTMEASURE	Linear moment	MomentPerLength	Real	Newton metre per metre	N m / m	N-M-PER-M	(1, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.LINEARMOMENTUNIT	❌	❌	✔️	✔️	✔️	❔	2	DECIDE QUDT has different name
IFCTHERMALCONDUCTIVITYMEASURE	Thermal conductivity	ThermalConductivity	Real	Watt per metre Kelvin	W / m K	W-PER-M-K	(1, 1, -3, 0, -1, 0, 0)	IFCDerivedUnitEnum.THERMALCONDUCTANCEUNIT	❌	❌	✔️	✔️	✔️	❔	2
IFCTHERMALTRANSMITTANCEMEASURE	Thermal transmittance	ThermalTransmittance	Real	Watt per square metre Kelvin	W / m² K	W-PER-M2-K	(0, 1, -3, 0, -1, 0, 0)	IFCDerivedUnitEnum.THERMALTRANSMITTANCEUNIT	❌	❌	✔️	✔️	✔️	❔	2
IFCTHERMALEXPANSIONCOEFFICIENTMEASURE	Thermal expansion coefficient	ThermalExpansionCoefficient	Real	Reciprocal kelvin	1 / K	PER-K	(0, 0, 0, 0, -1, 0, 0)	IFCDerivedUnitEnum.THERMALEXPANSIONCOEFFICIENTUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCLUMINOUSINTENSITYDISTRIBUTIONMEASURE	Luminous intensity distribution	LuminousIntensityDistribution	Real	Candela per lumen	cd / lm	CD-PER-LM		IFCDerivedUnitEnum.LUMINOUSINTENSITYDISTRIBUTIONUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCHEATINGVALUEMEASURE	Heating	HeatCapacity	Real	Joule per kelvin	J / K	J-PER-K	(2, 1, -2, 0, -1, 0, 0)	IFCDerivedUnitEnum.HEATINGVALUEUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE QUDT has different name
IFCSPECIFICHEATCAPACITYMEASURE	Specific heat capacity	SpecificHeatCapacity	Real	Joule per kilogram kelvin	J / Kg K	J-PER-KiloGM-K	(2, 0, -2, 0, -1, 0, 0)	IFCDerivedUnitEnum.SPECIFICHEATCAPACITYUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE remove word "specific"
IFCTEMPERATUREGRADIENTMEASURE	Temperature gradient	TemperatureGradient	Real	Kelvin per metre	K / m	K-PER-M	(-1, 0, 0, 0, 1, 0, 0)	IFCDerivedUnitEnum.TEMPERATUREGRADIENTUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCTEMPERATURERATEOFCHANGEMEASURE	Temperature rate of change	TemperatureChangeRate	Real	Kelvin per second	K / s	K-PER-SEC	(0, 0, -1, 0, 1, 0, 0)	IFCDerivedUnitEnum.TEMPERATURERATEOFCHANGEUNIT	❌	❌	❌	✔️	✔️	❔	3
IFCMASSPERLENGTHMEASURE	Mass per length	LinearMassDensity	Real	Kilogram per metre	Kg / m	KiloGM-PER-M	(-1, 1, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.MASSPERLENGTHUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCAREADENSITYMEASURE	Area density	AreaDensity	Real	Kilogram per squere metre	Kg / m²	KiloGM-PER-M2	(-2, 1, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.AREADENSITYUNIT	❌	❌	❌	✔️	✔️	❔	3
IFCMOLECULARWEIGHTMEASURE	Molecular weight	MolarMass	Real	Kilogram per mole	Kg / mol	KiloGM-PER-MOL	(0, 1, 0, 0, 0, -1, 0)	IFCDerivedUnitEnum.MOLECULARWEIGHTUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCMASSFLOWRATEMEASURE	Mass flow rate	MassFlowRate	Real	Kilogram per second	Kg / s	KiloGM-PER-SEC	(0, 1, -1, 0, 0, 0, 0)	IFCDerivedUnitEnum.MASSFLOWRATEUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCVAPORPERMEABILITYMEASURE	Vapor permeability	VaporPermeability	Real	Kilogram per second metre Pascal	Kg / s m Pa	KiloGM-PER-PA-SEC-M	(0, 0, 1, 0, 0, 0, 0)	IFCDerivedUnitEnum.VAPORPERMEABILITYUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE rename to "Permeability" (remove Vapor)
IFCROTATIONALMASSMEASURE	Rotational mass	RotationalMass	Real	Kilogram square metre	Kg m²	KiloGM-M2	(2, 1, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.ROTATIONALMASSUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCKINEMATICVISCOSITYMEASURE	Kinematic viscosity	KinematicViscosity	Real	Square metre per second	m² / s	M2-PER-SEC	(2, 0, -1, 0, 0, 0, 0)	IFCDerivedUnitEnum.KINEMATICVISCOSITYUNIT	❌	❌	✔️	✔️	✔️	❔	3	The SI unit (m2/s) doesn't match QUDT (stokes ST)
IFCISOTHERMALMOISTURECAPACITYMEASURE	Iso thermal moisture capacity	IsoThermalMoistureCapacity	Real	Cubic metre per kilogram	m³ / Kg	M3-PER-KiloGM	(3, -1, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.ISOTHERMALMOISTURECAPACITYUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCMOISTUREDIFFUSIVITYMEASURE	Moisture diffusivity	MoistureDiffusivity	Real	Cubic metre per second	m³ / s	M3-PER-SEC	(3, 0, -1, 0, 0, 0, 0)	IFCDerivedUnitEnum.MOISTUREDIFFUSIVITYUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE Merge with volumetric flow?
IFCVOLUMETRICFLOWRATEMEASURE	Volumetric flow rate	VolumetricFlowRate	Real	Cubic metre per second	m³ / s	M3-PER-SEC	(3, 0, -1, 0, 0, 0, 0)	IFCDerivedUnitEnum.VOLUMETRICFLOWRATEUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCSECTIONALAREAINTEGRALMEASURE	Sectional area integral	SectionalAreaIntegral	Real	Quintic metre	m⁵	M5	(5, 0, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.SECTIONALAREAINTEGRALUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCWARPINGCONSTANTMEASURE	Warping constant	WarpingConstant	Real	Sextic metre	m⁶	M6	(6, 0, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.WARPINGCONSTANTUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCIONCONCENTRATIONMEASURE	Ion concentration measure	IonConcentration	Real	Mole per cubic metre	mol / m³	MOL-PER-M3	(-3, 1, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.IONCONCENTRATIONUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCMODULUSOFELASTICITYMEASURE	Modulus of elasticity	ModulusOfElasticity	Real	Pascal	Pa	PA	(-1, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.MODULUSOFELASTICITYUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE Changed unit to Pascal. Consider also merging with Pressure (Pa)
IFCMODULUSOFLINEARSUBGRADEREACTIONMEASURE	Modulus of linear subgrade reaction	SubgradeModulus	Real	Pascal	Pa	N-PER-M3	(-1, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.MODULUSOFLINEARSUBGRADEREACTIONUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE Changed unit to Pascal. Consider also merging with Pressure (Pa)
IFCSHEARMODULUSMEASURE	Shear modulus	ShearModulus	Real	Pascal	Pa	PA	(-1, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.SHEARMODULUSUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE Changed unit to Pascal. Consider also merging with Pressure (Pa)
IFCMODULUSOFSUBGRADEREACTIONMEASURE	Modulus of subgrade reaction	SubgradeModulus	Real	Newton per cubic metre	N / m³	N-PER-M3	(-2, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.MODULUSOFSUBGRADEREACTIONUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCTORQUEMEASURE	Torque	Torque	Real	Newton metre	N m	N-M	(2, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.TORQUEUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCMODULUSOFROTATIONALSUBGRADEREACTIONMEASURE	Modulus of rotational subgrade reaction	ModulusOfRotationalSubgradeReaction	Real	Newton metre per metre radian	N m / m rad	N-M-PER-M-RAD	(1, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.MODULUSOFROTATIONALSUBGRADEREACTIONUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE same as with angle - degree or radians
IFCROTATIONALSTIFFNESSMEASURE	Rotational stiffness	RotationalStiffness	Real	Newton metre per radian	N m / rad	N-M-PER-RAD	(2, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.ROTATIONALSTIFFNESSUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE same as with angle - degree or radians
IFCWARPINGMOMENTMEASURE	Warping moment	WarpingMoment	Real	Newton square metre	N m²	N-M2	(3, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.WARPINGMOMENTUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCDYNAMICVISCOSITYMEASURE	Dynamic viscosity	DynamicViscosity	Real	Pascal second	Pa s	PA-SEC	(-1, 1, -1, 0, 0, 0, 0)	IFCDerivedUnitEnum.DYNAMICVISCOSITYUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCCURVATUREMEASURE	Curvature	Curvature	Real	Radian per metre	rad / m	RAD-PER-M	(-1, 0, 0, 0, 0, 0, 0)	IFCDerivedUnitEnum.CURVATUREUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE same as with angle - degree or radians
IFCANGULARVELOCITYMEASURE	Angular velocity	AngularVelocity	Real	Radian per second	rad / s	RAD-PER-SEC	(0, 0, -1, 0, 0, 0, 0)	IFCDerivedUnitEnum.ANGULARVELOCITYUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE same as with angle - degree or radians
IFCHEATFLUXDENSITYMEASURE	Heat flux density	HeatFluxDensity	Real	Watt per square metre	W / m²	W-PER-M2	(0, 1, -3, 0, 0, 0, 0)	IFCDerivedUnitEnum.HEATFLUXDENSITYUNIT	❌	❌	✔️	✔️	✔️	❔	3
IFCTHERMALADMITTANCEMEASURE	Thermal admittance	ThermalAdmittance	Real	Watt per square metre Kelvin	W / m² K	W-PER-M2-K	(0, 1, -3, 0, -1, 0, 0)	IFCDerivedUnitEnum.THERMALADMITTANCEUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE Consider merging with Thermal Transmittance
IFCCONTEXTDEPENDENTMEASURE	Context dependent		String						❌	❌	❔	❔	✔️	❌	⛔️	No need for dedicated measure.
IFCCOUNTMEASURE	Count		Integer						❌	❌	❔	❔	✔️	❌	⛔️	No need for dedicated measure. It is a simple integer property.
IFCDESCRIPTIVEMEASURE	Descriptive		String						❌	❌	❔	❔	✔️	❌	⛔️	No need for dedicated measure. It is a simple textual property.
IFCMONETARYMEASURE	Monetary		Real						❌	❌	❔	❔	✔️	❌	⛔️	No need for dedicated measure. It is a simple numeric property.
IFCNORMALISEDRATIOMEASURE	Normalised ratio		Real						❌	❌	❔	❔	✔️	❌	⛔️	No need for dedicated measure. It is a simple numeric property.
IFCNUMERICMEASURE	Numeric		Real						❌	❌	❔	❔	✔️	❌	⛔️	No need for dedicated measure. It is a simple numeric property.
IFCPOSITIVERATIOMEASURE	Positive ratio		Real						❌	❌	❔	❔	✔️	❌	⛔️	Restriction does not make it a separate measure.
IFCRATIOMEASURE	Ratio		Real						❌	❌	❔	❔	✔️	❌	⛔️	No need for dedicated measure. It is a simple numeric property.
IFCINTEGERCOUNTRATEMEASURE	Integer count rate		Integer						❌	❌	❔	❔	✔️	❌	⛔️	No need for dedicated measure. It is a simple integer property.
IFCSOUNDPOWERMEASURE	Sound power	SoundPower	Real	Watt	W	W		IFCDerivedUnitEnum.SOUNDPOWERUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE - One at the source (power), one at a distance from it (exposure)
IFCSOUNDPOWERLEVELMEASURE	Sound power level	SoundPowerLevel	Real	Decibel	db	DB		IFCDerivedUnitEnum.SOUNDPOWERLEVELUNIT	❌	❌	❌	✔️	✔️	❔	3	DECIDE - One at the source (power), one at a distance from it (exposure)
IFCSOUNDPRESSURELEVELMEASURE	Sound pressure level	SoundPressureLevel	Real	Decibel	db	DB		IFCDerivedUnitEnum.SOUNDPRESSURELEVELUNIT	❌	❌	❌	✔️	✔️	❔	3	DECIDE - One at the source (power), one at a distance from it (exposure)
IFCSOUNDPRESSUREMEASURE	Sound pressure	SoundPressure	Real	Pascal	Pa	PA		IFCDerivedUnitEnum.SOUNDPRESSUREUNIT	❌	❌	✔️	✔️	✔️	❔	3	DECIDE - One at the source (power), one at a distance from it (exposure)
IFCPOSITIVEPLANEANGLEMEASURE	Positive plane angle		Real	Radian	rad			IFCUnitEnum.PLANEANGLEUNIT	✔️	❌	✔️	✔️	✔️	❌	⛔️	Restriction does not make it a separate measure.
IFCROTATIONALFREQUENCYMEASURE	Rotational frequency		Real	Reciprocal kelvin	Hz		(0, 0, -1, 0, 0, 0, 0)	IFCDerivedUnitEnum.ROTATIONALFREQUENCYUNIT	❌	❌	✔️	✔️	✔️	❌	⛔️	Still a frequency.
IFCINTEGERCOUNTRATEMEASURE	Integer count rate		Integer	Reciprocal second	1 / s		(0, 0, -1, 0, 0, 0, 0)	IFCDerivedUnitEnum.INTEGERCOUNTRATEUNIT	❌	❌	✔️	✔️	✔️	❌	⛔️	Merge with Frequency (Hz)
IFCNONNEGATIVELENGTHMEASURE	Non-negative length		Real	Metre	m		(1, 0, 0, 0, 0, 0, 0)	IFCUnitEnum.LENGTHUNIT	✔️	❌	❌	✔️	✔️	❌	⛔️	Restriction does not make it a separate measure.
IFCPOSITIVELENGTHMEASURE	Positive length		Real	Metre	m		(1, 0, 0, 0, 0, 0, 0)	IFCUnitEnum.LENGTHUNIT	✔️	❌	✔️	✔️	✔️	❌	⛔️	Restriction does not make it a separate measure.
IFCPLANARFORCEMEASURE	Planar force		Real	Pascal	Pa		(-1, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.PLANARFORCEUNIT	❌	❌	✔️	✔️	✔️	❌	⛔️	Instead, use Pressure (Pa) or Force (N)
IFCLINEARSTIFFNESSMEASURE	Linear stiffness		Real	Newton per metre	N / m		(0, 1, -2, 0, 0, 0, 0)	IFCDerivedUnitEnum.LINEARSTIFFNESSUNIT	❌	❌	✔️	✔️	✔️	❌	⛔️	Merge with linear force

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