Non-uniqueness
Uncertainties in calibration of long stem platinum resistance thermometer according to the ITS-90.

For a given probe, the reduced resistance at a specified temperature can be obtained through various interpolation functions. For example, if we consider a temperature of 25°C, the calibration result will be different depending on whether the probe has been calibrated :

• the triple point of mercury, the triple point of water and the melting point of gallium ;

• the triple point of water and the melting point of gallium ;

• the triple point of water and the freezing point of indium ;

• the triple point of water, the freezing point of indium and the freezing point of tin;

• the triple point of water, the freezing point of tin and the...