(1) Every unit of weight or measure shall be based on the units of the metric system.
(2) For the purpose of sub-section (1),
(a) the international system of units as recommended by the General Conference on Weights and Measures, and
(b) such additional units as may be recommended by the International Organisation of Legal Metrology,
shall be the units of the metric system.
Section 5 - Base unit of length
(1) The base unit of length shall be the metre.
(2) The "metre" is the length equal to 1650 763.73 wave lengths in vacuum of the radiation corresponding to the transition between the levels 2p10 and 5d5 of the krypton-86 atom.
Section 6 - Base unit of mass
(1) The base unit of mass shall be the kilogram.
(2) The "kilogram" is the unit of mass; it is equal to the mass of the international prototype of the kilogram.
Section 7 - Base unit of time
(1) The base unit of time shall be the second.
(2) The "second" is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.
Section 8 - Base unit of electric current
(1) The base unit of electric current shall be the ampere.
(2) The "ampere" is that constant current which if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one metre apart in vacuum, would produce between these conductors a force equal to 2 x 107newton per metre of length.
Section 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.
Section 10 - Base unit of luminous intensity
(1) The base unit of luminous intensity shall be the candela.
(2) The "candela" is the luminous intensity, in the perpendicular direction, of a surface of 1/600,000 square metre of a black body at the temperature of freezing platinum under a pressure of 101 325 newtons per square metre.
Section 11 - Base unit of amount of substance
(1) The base unit of amount of substance shall be the mole.
(2) The "mole" is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12.
(3) When the mole is used, the elementary entities shall invariably be specified and may be atoms, molecules ions, electrons, other particles, or specified groups of such particles.
Section 12 - Supplementary, derived, special and other units of weight or measuretheir symbols, definitions, etc.
(1) The Central Government may, by rules made in this behalf, specify, in relation to the base units of weight or measure, such supplementary, derived, or other units or standard symbols or definitions as the General Conference on Weights and Measures or the International Organisation of Legal Metrology may recommend.
Explanation."Derived unit" means a unit which is derived from the base, or supplementary, units, or both.
(2) The Central Government may, by rules made in this behalf, specify such multiples and sub-multiples of, and physical constants, and ratios or co-efficients in relation to, units of weight or measure as the General Conference on Weights and Measures or the International Organisation of Legal Metrology may recommend.
(3) The Central Government may, by notification, declare, for such period as it may consider necessary such special units of weight or measure as the General Conference on Weights and Measures or the International Organisation of Legal Metrology may recommend.
Section 13 - Base unit of numeration
(1) The base unit of numeration shall be the unit of the international form of Indian numerals.
(2) Every numeration shall be made in accordance, with the decimal system.
(3) The decimal multiples and sub-multiples of the numerals shall be of such denominations and be written in such manner as the Central Government may, after previous publication, specify by rules made in this behalf:
Provided that no such rule shall be made before the expiry of six months from the date on which the draft of the proposed rules was first published in the Official Gazette.
Section 14 - Standard unit of weight or measure
(1) The base unit of mass specified in section 6 and base units of measures specified in sections 5 and sections 7 to 11 (both inclusive) and the supplementary and other units specified by rules made under section 12, shall be the standard units of weight or measure, as the case may be.
(2) The units of numeration specified by or under section 13 shall be the standard units of numeration.