Where, for any legal purpose:
(a) it is necessary to convert a measurement of a physical quantity expressed in terms of one of the Australian legal units of measurement of that physical quantity to a measurement expressed in terms of another Australian legal unit of measurement; or
(b) it is necessary to convert a measurement of a physical quantity expressed in terms of a unit of measurement (not being an Australian legal unit of measurement) of that physical quantity to a measurement expressed in terms of one of the Australian legal units of measurement;
the prescribed conversion factors shall, where applicable, be used.