Section 16(5) in The Standards of Weights and Measures (National Standards) Rules, 1988
(5);The value of the national prototype and other national standards shall be the value determined by the National Physical Laboratory or assigned by the National Physical Labora-tory on the basis of the technical information provided by the International Bureau of Weights and Measures. The National Physical Laboratory shall publish such values periodically but in any case at least once in every five years.
