For subsection 150N (1) of the Petroleum (Submerged Lands) Act 1967, for the purposes of describing, in a title or other instrument under the Act, the position on the surface of the Earth of a point, line or area: (a) the current datum is the Geocentric Datum of Australia; and (b) the current datum replaces the previous datum. For subsection 150R (1) of the Act, the Designated Authority may issue an instrument varying a permit in force immediately before the changeover time for the sole purpose