A1 A2 A3 A4 A5 Bookmark ruler wire hanging in spiral binding Book diaries, school planners, system planners, organizers. The bookmark ruler can be used in all diaries, school planners, system planners, organizers and notepads that have been bound with either a wire binder binding (3:1 or 2:1 pitch) or a plastic coil (4:1 pitch) and are at least 210 mm high.