law: Standards of Weights and Measures Act, 1976 
  9. Base unit of
  
  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
  
  Celsius corresponds to 273.15 Kelvin.
  (5) The degree Celsius
  
  may also be used for expressing the interval or difference of temperature, unit
  
  degree Celsius being equal to unit Kelvin. ]