Some cables are "mirrored" or "clocked" with a pattern that is known throughout the telephone industry. Starting with the first binder group in the center, the technician counts the cable's groups in a spiral direction depending on the location of the central office or switch. If looking at the cable's core and the switch is in that direction, the groups are counted counter-clockwise. If the cable is the "field side", the count is clockwise. There are indicators on the mylar ribbons to know where to begin for each layer and a diagram for the different cable sizes should be readily available for reference.