Section 9 in The Standards Of Weights And Measures Act, 1976 [Entire Act]
thermodynamic temperature
(1) The base unit of thermodynamic temperature shall be the kelvin. (2) The kelvin is the fraction 1/273.16 of the thermodynamic ... temperature of the triple point of water. (3) The kelvin shall also be used for expressing the interval or difference of temperature. (4) Zero degree