Section 12(2) in The Standards of Weights and Measures (National Standards) Rules, 1988
(2)Ordinarily, the coefficients and their respective symbols specified in Schedule X shall be used:Provided that any coefficient which is not specified in Schedule X but which corresponds to any coefficient specified in that Schedule, may be used for a period of five years from the commencement of these rules:Provided further where any new coefficient added in Schedule X, any coefficient corresponding to the coefficient so added may be used for a period of five years from the date of addition of such coefficient.
