NCSLI MII taxonomy

Measurand taxonomy

One agreed name for what each calibration measures or sources, so software, certificates and scopes mean the same thing. Measure.Voltage.DC is a DMM reading DC volts; Source.Voltage.DC is a calibrator putting them out. Each taxon lists its result quantity and the parameters that pin the measurand down.

136 current taxa (73 Measure, 63 Source) from the NCSLI MII Measurand Taxonomy Catalog, maintained by NCSL International’s Measurement Information Infrastructure committee. Your AI can search it too: see Use with AI.

Upstream commit
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Catalog last changed
2026-07-29
Pulled by Metrology Bench
2026-10-28 · checked nightly

Every night we check github.com/NCSLI-MII/measurand-taxonomy for a new commit to MeasurandTaxonomyCatalog.xml, rebuild this section from it and keep the XML byte for byte (SHA-256 55538bf3e6dc…). To propose a new taxon, open an issue upstream.

136 of 136 taxa

  • Measure.Acceleration

    To measure the acceleration or deceleration / the change in velocity of a body. (m/s²)

    accelerationVibration

  • Measure.Capacitance

    The measurement of the capacitance of a device.

    capacitanceElectrical

  • Measure.Charge.DC

    This process measures electric charge sourced in direct-current mode.

    charge

  • Measure.Conductance

    The process of measuring the Electrical Conductance of a device.

    conductanceElectrical

  • Measure.Conductivity

    The process of measuring the Electrical Conductivity of a Solution or a device.

    conductivityChemical

  • Measure.Current.AC

    The process measures the AC Current sourced by a device without knowing the shape of the signal. Values can only be tested in RMS because the shape of the signal is unknown.

    currentElectrical

  • Measure.Current.AC.Sinewave

    The process measures the AC Current sourced by a device without knowing the shape of the signal is a sinewave. Knowing the shape of the waveform allows the system to make conver…

    currentElectrical

  • Measure.Current.AC.Squarewave

    The process measures the Squarewave Current sourced by a device with the assumption it is generating an AC Squarewave. Knowing the shape of the waveform allows the system to mak…

    currentElectrical

  • Measure.Current.AC.Trianglewave

    The process measures the Alternating Current sourced by a device with the assumption it is generating an AC Trianglewave. Knowing the shape of the waveform allows the system to …

    currentElectrical

  • Measure.Current.DC

    The process measures the Direct Current (or DC) sourced by a device.

    currentElectrical

  • Measure.DensityMass.Gas

    Test Process that measures a gas’s density as defined by the amount of mass present in a specified volume of gas at a given temperature and pressure. Gases are extremely respons…

    density-massMass

  • Measure.DensityMass.Liquid

    Test Process that measures a liquid’s density as defined by the amount of mass present in a specified volume of liquid at a given temperature. Temperature affects density, as do…

    density-massMass

  • Measure.DensityMass.Solid

    Test Process that measures a solid’s density as defined by the amount of mass present in a specified volume temperature. Temperature affects density as solids expand and contrac…

    density-massMass

  • Measure.Force

    Test Process that measures the Force as defined as mass times acceleration (F = m * a). The formula describes a free mass or the net force on any mass. Dead-weight force measure…

    forceMass

  • Measure.Frequency

    The process of measuring the frequency of a signal.

    frequencyElectrical

  • Measure.Frequency.AmplitudeModulation.Rate

    The process of measuring the demodulated frequency rate of an Amplitude Modulate (AM) signal.

    frequencyElectrical

  • Measure.Frequency.Arbitrary.Cardiograph

    The process of measuring an arbitrary Cardiograph waveform frequency.

    frequencyTime and Frequency

  • Measure.Frequency.FrequencyModulation.Deviation

    This process measures the Deviation Frequency of a Frequency Modulated (FM) signal. The deviation is used to describe the maximum difference between an FM modulated frequency …

    frequencyElectrical

  • Measure.Frequency.FrequencyModulation.Rate

    The process of measuring the Demodulated Rate of a Frequency Modulated (FM) Signal.

    frequencyElectrical

  • Measure.Frequency.PhaseModulation.Rate

    The process of measuring the demodulated frequency rate of a phase-modulated RF signal.

    frequencyElectrical

  • Measure.Impedance

    The process of measuring the impedance of a device.

    impedanceElectrical

  • Measure.Inductance

    The process of measuring the Inductance of a device.

    inductanceElectrical

  • Measure.Length

    Length is the straight-line distance between two points. It can be measured in one, two, or three dimensions with 6 degrees of freedom. Length measurements are made from Point …

    lengthDimensional

  • Measure.Length.Circumference

    Length Circumference is the length measured around the inside or outside of a round or circular object.

    lengthDimensional

  • Measure.Length.Diameter

    Length Diameter is the edge-to-edge straight-line distance passing through the center of a circular object. It can measure the inside open space or outside diameter of the object.

    lengthDimensional

  • Measure.Length.Form.Flatness

    The minimum normal (perpendicular) distance between two parallel planes that fully contain a surface. Commonly, the two parallel planes may be constructed from the surface itsel…

    lengthDimensional

  • Measure.Length.Form.Parallelism

    Parallelism is a fairly common symbol that requires the referenced surface or line to be parallel to a datum surface or line. Parallelism can reference a 2D line, but more commo…

    lengthDimensional

  • Measure.Length.Form.Perpendicularity

    Perpendicularity is a fairly common symbol that requires the referenced surface or line to be perpendicular or 90° from a datum surface or line. Perpendicularity can reference a…

    lengthDimensional

  • Measure.Length.Form.Roughness

    Roughness is the measure of the finer surface irregularities in the surface texture (texture comprises roughness, waviness, and form), either along a profile (line) or across a …

    lengthDimensional

  • Measure.Length.Form.Roundness

    Roundness is the feature described as deviation (radial error) from true roundness (mathematically, a circle).

    lengthDimensional

  • Measure.Length.Form.Sphericity

    Sphericity is a measure of how closely the shape of an object resembles that of a perfect sphere. For example, the sphericity of the balls inside a ball bearing determines the q…

    lengthDimensional

  • Measure.Length.Form.Straightness.Axis

    The minimum diameter of a cylinder that fully contains a specified line.

    lengthDimensional

  • Measure.Length.Form.Straightness.Surface

    The minimum normal (perpendicular) distance between two parallel planes that fully contain a surface along a specified line.

    lengthDimensional

  • Measure.Length.Radius

    Length Radius commonly thought of as half the diameter of a full circle, the radius is the distance from the center point to the edge of an arc or partial circle.

    lengthDimensional

  • Measure.Mass.Conventional

    Test Process that measures the conventional value of the result of weighing a body in air equals the mass of a standard that balances this body under the following conventionall…

    massMass

  • Measure.Mass.True

    Test Process that measures the quantity of matter which a body contains, as measured by its acceleration under a given force or by the force exerted on it by a gravitational fie…

    massMass

  • Measure.Phase-Noise.Sideband

    A test process of measuring power spectral density offset from the carrier as compared to the carried power.

    phase-noiseElectrical

  • Measure.Phase.PhaseModulation

    The process of measuring the phase-modulated component of a phase-modulated RF signal typically in radians.

    phaseElectrical

  • Measure.Phase.ReflectionFactor.RF

    The process of measuring the Reflection Coefficient Phase of an RF signal that is reflected back to the transmitting port.

    phaseElectrical

  • Measure.Phase.TransmissionFactor

    The process of measuring the Transmission Coefficient Phase of an RF signal that transmitted through the device under test.

    phaseElectrical

  • Measure.Power.RF.Sinewave

    A test process that measures the RF power of a signal. It can be either direct or monitored by an RF Power measurement device

    powerElectrical

  • Measure.Power.Ultrasonic

    The time-average ultrasonic power emitted by an ultrasonic transducer. The measurement of ultrasonic power in liquid is based on the measurement of radition force using a gravi…

    powerAcoustics, ultrasound and vibration

  • Measure.Pressure.Differential.Static

    This test process measures the pneumatic differential pressure between two points generated by the unit under test. The resulting pressure difference will return in the unit of…

    pressurePressure

  • Measure.Pressure.Hydraulic.Static

    This test process measures the hydraulic pressure generated by the unit under test. The resulting measured will be in the unit of measure as defined in the test point’s data. No…

    pressurePressure

  • Measure.Pressure.Pneumatic.Absolute.Static

    This test process measures the pneumatic absolute pressure generated by the unit under test. The resulting measured will be in the unit of measure as defined in the test point’s…

    pressurePressure

  • Measure.Pressure.Pneumatic.Gage.Static

    This test process measures the pneumatic gage (or relative pressure) generated by the unit under test. The resulting measured will be in the unit of measure as defined in the te…

    pressurePressure

  • Measure.Ratio.AmplitudeModulation

    The process of measuring the Percent of Modulation of an Amplitude Modulation (AM) Signal.

    ratioElectrical

  • Measure.Ratio.DensityMass

    Test Process that measures the relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference mate…

    ratioMass

  • Measure.Ratio.Humidity.Relative

    Measuring the ratio of the water vapor’s partial pressure divided by the saturation water vapor pressure allowed at a given temperature.

    ratioThermodynamics

  • Measure.Ratio.Humidity.Specific

    Measuring the ratio of the mass of water vapor to the total mass of the dry air. The gravimetric method of calibration determines the specific humidity, with pressure and temper…

    ratioThermodynamics

  • Measure.Ratio.Power.RF.Sinewave.Delta.Frequency

    A test process that measures the difference between 2 sinusoidal RF signals at different frequencies while keeping the power levels constant. The two measured values are compa…

    powerElectrical

  • Measure.Ratio.Power.RF.Sinewave.Delta.Power

    A test process that measures the difference 2 sinusoidal RF signals at different power levels keeping the frequency constant. The two measured values are compared, the results…

    ratioElectrical

  • Measure.Ratio.Power.ReflectionFactor.RF

    The process of measuring the Reflection Coefficient magnitude of an RF signal that is reflected back to the transmitting port.

    ratioElectrical

  • Measure.Ratio.Power.TransmissionFactor

    The process of measuring the Transmission Coefficient magnitude of an RF signal that transmitted through the device under test. It is represented as a ratio of power received o…

    ratioElectrical

  • Measure.Ratio.Torque

    A ratio of an instrument’s torque output to the torque applied to the input, e.g., a torque multiplier’s output torque divided by its input torque

    torqueTorque

  • Measure.Ratio.Voltage.AC.Ripple.OnDC

    A test process that measures the ratio between the AC ripple & noise in RMS voltage measured on a DC signal then divided by the DC voltage level creating a ratio between the two…

    ratioElectrical

  • Measure.Ratio.Voltage.AC.Sinewave.Delta.Frequency

    A test process that measures the amplitude-response difference between two sinusoidal AC sinewave signals at different frequencies while keeping the source voltage level constan…

    voltageElectrical

  • Measure.Ratio.Voltage.AC.Sinewave.Delta.Voltage

    A test process that measures the difference between sinusoidal AC sinewave signals at different voltage levels keeping the frequency constant. The two measured values are compar…

    ratioElectrical

  • Measure.Resistance

    The process of measuring the resistance of a resister or other device.

    resistanceElectrical

  • Measure.Temperature

    The process of measuring the physical temperature of a device.

    temperatureThermodynamics

  • Measure.Temperature.Radiometric

    The process of measuring the physical temperature from a block body that will be used to generate infrared temperatures.

    temperatureThermodynamics

  • Measure.Temperature.Simulated.PRT

    The process of measuring the simulated temperature in voltage from a PRT or SPRT device.

    temperatureThermodynamics

  • Measure.Temperature.Simulated.RTD

    The process of measuring the simulated temperature in voltage from a RTD device.

    temperatureThermodynamics

  • Measure.Temperature.Simulated.Thermocouple

    The process of measuring the simulated temperature in voltage from a thermocouple device.

    temperatureThermodynamics

  • Measure.Time

    The process of measuring the current time using the Universal Time Coordinated / Coordinated Universal Time.

    timeTime and Frequency

  • Measure.Time.Transition

    The process of measuring the pulse transition time of a square wave signal. The transition can be either be in a positive direction (Risetime) or a negative direction (Fall time).

    timeElectrical

  • Measure.Torque

    A test process measuring the accuracy of a torque wrench or other torquing device.

    torqueTorque

  • Measure.Torque.HydraulicPressure

    A test process that measures the accuracy of hydraulic torque wrenches where hydraulic pressure is applied to the torque wrench and it applies a known torque to the nut or bolt …

    torqueTorque

  • Measure.Voltage.AC

    The process measures the AC RMS (Root-Mean-Square) voltage sourced by the UUT. Values can only be expressed in RMS because the shape of the signal is no known.

    voltageElectrical

  • Measure.Voltage.AC.Ripple.OnDC

    A test process that measures the RMS AC voltage ripple or noise on a DC signal.

    voltageElectrical

  • Measure.Voltage.AC.Squarewave

    The process measures the AC RMS (Root-Mean-Square) voltage sourced by the UUT. Because the shape is known the values can be converted to Volts PeakToPeak.

    voltageElectrical

  • Measure.Voltage.AC.Trianglewave

    The process measures the AC RMS (Root-Mean-Square) voltage sourced by the UUT. Because the shape is known the values can be converted to Volts PeakToPeak.

    voltageElectrical

  • Measure.Voltage.DC

    This test process measures the DC (Direct Current) voltage sourced from the UUT.

    voltageElectrical

  • Source.Acceleration

    UUT is placed in a device then the device accelerates to a known Acceleration (m/s²) Often this is tested by measuring the DC output of an accelerometer on a centrifuge.

    accelerationVibration

  • Source.Acceleration.Shock

    UUT is placed in a device, normally a shaker, which then moves in a single axis direction at a known acceleration at the reference frequency. Then the amplitude is changed and t…

    accelerationVibration

  • Source.Acceleration.Vibration

    UUT is placed in a device, normally a shaker, then the shaker moves in a single access direction at a known acceleration and frequency.

    accelerationVibration

  • Source.Capacitance

    This is the process of generating a known capacitance.

    capacitanceElectrical

  • Source.Conductance

    The process of sourcing Electrical Conductance either from a fixed device or simulated.

    conductanceElectrical

  • Source.Conductivity

    The process of sourcing Electrical Conductivity either from a fixed device or simulated.

    conductivityElectrical

  • Source.Current

    The process of sourcing a Direct Current) voltage from a device and measuring the value on the UUT.

    currentElectrical

  • Source.Current.AC.Sinewave

    The process of sourcing a Sinusoidal Alternating Current signal. Knowing the shape of the waveform allows the system to make conversions from RMS to PeakToPeak.

    currentElectrical

  • Source.Current.AC.Squarewave

    The process of sourcing a Squarewave Alternating Current signal. Knowing the shape of the waveform allows the system to make conversions from RMS to PeakToPeak.

    currentElectrical

  • Source.Current.AC.Trianglewave

    The process of sourcing a Triangle Alternating Current signal. Knowing the shape of the waveform allows the system to make conversions from RMS to PeakToPeak.

    currentElectrical

  • Source.DensityMass.Gas

    Test Process that sources a gas’s density as defined by the amount of mass present in a specified volume of gas at a given temperature and pressure. Gases are extremely responsi…

    density-massMass

  • Source.DensityMass.Liquid

    Test Process that sources a liquid’s density as defined by the amount of mass present in a specified volume of liquid at a given temperature. Temperature affects density, as doe…

    density-massMass

  • Source.DensityMass.Solid

    Test Process that sources a solid’s density as defined by the amount of mass present in a specified volume temperature. Temperature affects density as solids expand and contract…

    density-massMass

  • Source.Force

    Test Process that sources a Force as defined as mass times acceleration (F = m * a). The formula describes a free mass or the net force on any mass. Dead-weight force measuremen…

    forceMass

  • Source.Frequency.AC.Sinewave

    The process of generating a frequency-stable sinewave waveform.

    frequencyElectrical

  • Source.Frequency.AC.Squarewave

    The process of generating a frequency-stable square waveform.

    frequencyElectrical

  • Source.Frequency.RF.Sinewave

    The process of generating a frequency-stable RF Sinewave waveform.

    frequencyElectrical

  • Source.Impedance

    The process of measuring the impedance of a device.

    impedanceElectrical

  • Source.Inductance

    The process of sourcing electrical Inductance of a device either fixed or simulated.

    inductanceElectrical

  • Source.Length

    Length is the straight-line distance between two points. It can be measured in one, two, or three dimensions with 6 degrees of freedom. Length measurements are made from Point …

    lengthDimensional

  • Source.Length.Circumference

    Length Circumference is the length measured around the inside or outside of a round or circular object.

    lengthDimensional

  • Source.Length.Diameter

    Length Diameter is the edge-to-edge straight-line distance passing through the center of a circular object. It can measure the inside open space or outside diameter of the object.

    lengthDimensional

  • Source.Length.Form.Perpendicularity

    Perpendicularity is a fairly common symbol that requires the referenced surface or line to be perpendicular or 90° from a datum surface or line. Perpendicularity can reference a…

    lengthDimensional

  • Source.Length.Form.Roundness

    Roundness is the feature described as deviation (radial error) from true roundness (mathematically, a circle).

    lengthDimensional

  • Source.Length.Form.Sphericity

    Sphericity is a measure of how closely the shape of an object resembles that of a perfect sphere. For example, the sphericity of the balls inside a ball bearing determines the q…

    lengthDimensional

  • Source.Length.Form.Straightness.Surface

    The minimum normal (perpendicular) distance between two parallel planes that fully contain a surface along a specified line.

    lengthDimensional

  • Source.Length.Radius

    Length Radius commonly thought of as half the diameter of a full circle, the radius is the distance from the center point to the edge of an arc or partial circle.

    lengthDimensional

  • Source.MassFlowRate.Gas

    This process sources a reference mass flow rate of gas for calibrating gas-flow meters. The instantaneous mass flow rate q_m equals dm/dt, sometimes estimated as ∆m/∆t using the…

    flow-mass

  • Source.Mass.Conventional

    Test Process that sources a conventional value of the result of weighing a body in air equals the mass of a standard that balances this body under the following conventionally c…

    massMass

  • Source.Mass.True

    Test Process that sources a quantity of matter which a body contains, as measured by its acceleration under a given force or by the force exerted on it by a gravitational field.…

    massMass

  • Source.Power.AC.Sinewave

    The process of sourcing a sinusoidal AC Power signal from a device and measuring the value on the UUT. This test process can be used by any device that measures absolute AC power.

    powerElectrical

  • Source.Power.AC.Sinewave.Simulated

    The process of sourcing a sinusoidal AC Power signal from a device where the Volts and Amps are provided on two different outputs and measured by the UUT as Watts / Power. This …

    powerElectrical

  • Source.Power.DC

    The process of sourcing DC Power signal from a device and measuring the value on the UUT. This test process can be used by any device that measures absolute DC power.

    powerElectrical

  • Source.Power.DC.Simulated

    The process of sourcing a sinusoidal DC Power signal from a device where the Volts and Amps are provided on two different outputs and measured by the UUT as Watts / Power. This …

    powerElectrical

  • Source.Power.Noise.Terminated

    This process connects a Termination to the input of a measurement device to reduce the noise and outside electrical signals. The test process is typically used to measure the UU…

    powerElectrical

  • Source.Power.RF.Sinewave

    powerElectrical

  • Source.Pressure.Hydraulic.Static

    This test process generates the hydraulic pressure to be measured by the unit under test. The resulting measured will be in the unit of measure as defined in the test point’s da…

    pressurePressure

  • Source.Pressure.Pneumatic.Absolute.Static

    This test process generates the pneumatic absolute pressure to be measured by the unit under test. The resulting measured will be in the unit of measure as defined in the test p…

    pressurePressure

  • Source.Pressure.Pneumatic.Differential.Static

    This test process generates two pneumatic pressures with a known differential pressure between two points measured by the unit under test. The resulting differential pressure w…

    pressurePressure

  • Source.Pressure.Pneumatic.Gage.Static

    This test process generates the pneumatic gage pressure (or relative pressure) to be measured by the unit under test. The resulting measured will be unit of measure as defined i…

    pressurePressure

  • Source.Ratio.Acceleration.Delta.Amplitude

    UUT is placed in a device, normally a shaker, which then moves in a single axis direction at a known acceleration at the set frequency. Then the amplitude is changed and the dif…

    ratioVibration

  • Source.Ratio.Acceleration.Delta.Frequency

    UUT is placed in a device, normally a shaker, which then moves in a single axis direction at a known acceleration at the reference frequency. Then the frequency is changed to th…

    ratioVibration

  • Source.Ratio.Humidity

    The generation of humidity as a ratio of the total mass of the water vapor divided by the total volume of air. This is also called volumetric humidity.

    ratio

  • Source.Ratio.Power.RF.Sinewave.Delta.Frequency

    A test process the sources 2 sinusoidal RF signals at different frequencies keeping the power levels constant between the two frequencies. The FrequencyRef signal is sourced an…

    ratioElectrical

  • Source.Ratio.Power.RF.Sinewave.Delta.Power

    ratioElectrical

  • Source.Ratio.Voltage.AC.Sinewave.Delta.Frequency

    A test process the sources two sinusoidal AC Voltage signals at different frequencies keeping the voltage levels constant between the two frequencies. The FrequencyRef signal is…

    ratioElectrical

  • Source.Ratio.Voltage.AC.Sinewave.Delta.Voltage

    A test process that sources two sinusoidal AC Voltage signals at different voltage levels keeping the frequency constant. The ReferenceVoltage signal is sourced and the voltage …

    ratioElectrical

  • Source.Resistance

    The process of sourcing electrical Resistance of a device either fixed or simulated.

    resistanceElectrical

  • Source.Temperature

    The process of generating a physical temperature to be measured by a device.

    temperatureThermodynamics

  • Source.Temperature.FixedPoint.ITS90

    The process of generating a physical temperature buy observing the triple point or melting point of a specified substance under a known pressure or atmosphere. Wiki - Triple Poi…

    temperatureThermodynamics

  • Source.Temperature.Radiometric

    The process of generating an infrared temperature on a block body to be measured by an infrared measuring device.

    temperatureThermodynamics

  • Source.Temperature.Simulated.PRT

    The process of generating resistance simulating temperature to be measured by a PRT or SPRT temperature measuring device.

    temperatureThermodynamics

  • Source.Temperature.Simulated.RTD

    The process of generating resistance simulating temperature to be measured by an RTD temperature measuring device.

    temperatureThermodynamics

  • Source.Temperature.Simulated.Thermocouple

    The process of generating a simulated temperature in voltage representing a temperature to be measured by a device.

    temperatureThermodynamics

  • Source.Time.Marker

    The process of generating a period-stable pulsed marker waveform.

    timeTime and Frequency

  • Source.Time.Squarewave

    The process of generating a period-stable square waveform.

    timeTime and Frequency

  • Source.Torque

    A test process of generating a known torque.

    torqueTorque

  • Source.Voltage.AC.Sinewave

    The process of sourcing a sinusoidal AC Voltage signal from a device and measuring the value on the UUT. This test process can be used by any device that measures absolute AC Vo…

    voltageElectrical

  • Source.Voltage.DC

    The process of sourcing a DC (Direct Current) voltage from a device and measuring the value on the UUT.

    voltageElectrical

  • Source.Voltage.DC.Delta.Voltage

    The process of sourcing two DC (Direct Current) voltage signals. First the ReferenceVoltage signal is sourced and measured on the UUT, that value is stored as reference. Then th…

    voltageElectrical

  • Source.Voltage.Noise.Terminated

    This process connects a Termination to the input of a measurement device to measure the no signal applied voltage /noise at the inpu. The test process is typically used to meas…

    voltageElectrical

  • Source.Voltage.Shorted

    This process connects a Short to the input of a measurement device and measures the no signal applied Voltage. This is The test process is typically used to measure the UUT’s Z…

    voltageElectrical

  • Source.VolumeFlowRate.Gas

    This process sources a reference volume flow rate of gas for calibrating gas-flow meters. The instantaneous volumetric flow rate q_V equals dV/dt, sometimes estimated as ∆V/∆t u…

Recent upstream changes

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