Entry category abbreviations: ALL = all bands, CK = check log, HP = high power (total output power greater than 100 Watts), LP = low power (total output power no more than 100 Watts), QRP = reduced power (total output power no more than 5W), M1 = multiple operators and single transmitter, M2 = multiple operators and two transmitters, MS = multi-single, MM = multiple operators and multiple transmitters, SO = single operator, and SWL = shortwave listener. Note: the M1 and M2 categories replaced the MS category in 2010, the LP and HP categories were introduced in 2010, and the QRP categories were introduced in 2014