The following callsign blocks are currently in use:
Class A (Advanced): 4X1 and 4Z1 callsign series
Class B (General): 4X4, 4X5, 4X6, 4Z4 and 4Z5 callsigns (with a 2 letter suffix). Some Advanced ops prefer to keep their General callsign.
Class C (Novice): 4Z9 callsigns (3 letter suffix)
Class D (Technician): 4Z7 callsigns (3 letter suffix) – no longer issued.
Other formats:
4Xna or 4Zna (examples: 4X4S, 4X7T) – contest calls and special event stations
4X, 4Z followed by a number and letters – special event stations
