For the purposes of this Act, the surface of the Earth is taken to be divided--
(a) by the meridian of Greenwich and by meridians of longitude that are at a distance from that meridian of 5 minutes, or a multiple of 5 minutes, of longitude, and
(b) by the equator and by parallels of latitude that are at a distance from the equator of 5 minutes, or a multiple of 5 minutes, of latitude,into graticular sections, each of which is bounded--
(c) by portions of 2 of those meridians that are at a distance from each other of 5 minutes of longitude, and
(d) by portions of 2 of those parallels that are at a distance from each other of 5 minutes of latitude.