DA1: Station is directional at all times and uses the same pattern at all times.
DA2: Station is directional at all times and uses different patterns for daytime and night.
DA3: Station is directional at all times and uses different patterns for daytime, critical hours*, and night.
DAD: Station is directional in the daytime only.
DAN: Station is directional at night only.
ND1 or ND2: Station is non-directional.
NDD: Station is non-directional and operates during daytime only.
*"Critical hours" are from sunrise to 2 hours after sunrise and from 2 hours before sunset to sunset.