Before revision: The precise spacing is defined by dividing the world into zones based on latitude, and is given in the following table: zone latitude range level 0 (arc secs) level 1 (arc secs) level 2 (arc secs) latitude spacing all 30 3 1 longitude spacing I 0°–50° (North–South) 30 3 1 II 50°–70° (North–South) 60 6 2 III 70°–75° (North–South) 90 9 3 IV 75°–80° (North–South) 120 12 4 V 80°–90° (North–South) 180 18 6 In addition three more levels (3, 4 and 5) at increasing resolution have been proposed, but not yet standardized.
After revision: The precise spacing is defined by dividing the world into zones based on longitude, and is given in the following table: zone latitude range level 0 (arc secs) level 1 (arc secs) level 2 (arc secs) latitude spacing all 30 3 1 latitude spacing I 0°–50° (North–South) 30 3 1 II 50°–70° (North–South) 60 6 2 III 70°–75° (North–South) 90 9 3 IV 75°–80° (North–South) 120 12 4 V 80°–90° (North–South) 180 18 6 In addition three more levels (3, 4 and 5) at increasing resolution have been proposed, but not yet standardized.