Section 3:

3. Units to be used (1) Subject to subsection (4), the measurement of any quantity shall be expressed in terms of SI units. (2) The SI units shall consist of— (a) base units; (b) supplementary units; and (c) derived units. I19 – 1 [Issue 1] International System of Units (SI) Act (3) For the purposes of subsection (2)— (a) base units— (i) are units specified in the second column; (ii) shall be used in respect of the corresponding quantity specified in the first column, of the First Schedule; (b) supplementary units— (i) are units specified in the second column; (ii) shall be used in respect of the corresponding quantity specified in the first column, of the Second Schedule; (c) derived units— (i) are units which are derived from base units or supplementary units or both; (ii) (A) include the units specified in the second column; (B) shall be used in respect of the corresponding quantity specified in the first column, of the Third Schedule. (4) The units specified in the second column of the Fourth Schedule may be used for the measurement of the corresponding quantity specified in the first column of that Schedule.