Section 2(h) in The Standards of Weights and Measures (National Standards) Rules, 1988
(h);"SI prefix" means the name and symbol of a prefix used for forming decimal multiples and sub-multiples of SI units, and of such other units as are permitted subject to any exception or modification by the General Conference on Weights and Measures or the International Organisation of Legal Metrology, or both, to be used along with the SI units;
