Before revision: The precise spacing is defined by dividing the world into zones based on latitude, and is given in the following tables: Zone latitude I 0°–50° (North–South) II 50°–70° (North–South) III 70°–75° (North–South) IV 75°–80° (North–South) V 80°–90° (North–South) level 0 (arc secs) level 1 (arc secs) level 2 (arc secs) latitude spacing 30 3 1 zone I longitude spacing 30 3 1 zone II longitude spacing 60 6 2 zone III longitude spacing 90 9 3 zone IV longitude spacing 120 12 4 zone V longitude spacing 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 latitude, and is given in the following tables: table: zone latitude range level 0 (arc secs) level 1 (arc secs) level 2 (arc secs) latitude spacing all 0°–90° (North–South) 30 3 1 longitude spacing I 0°–50° (North–South) II 50°–70° (North–South) III 70°–75° (North–South) IV 75°–80° (North–South) V 80°–90° (North–South) 30 3 160 6 290 9 3120 12 4 180 18 6 In addition three more levels (3, 4 and 5) at increasing resolution have been proposed, but not yet standardized.