Argosy Code 145, known in short as "AC 145", is an emergency alert that is used by the Systems Commonwealth's High Guard. The code indicates to friendly forces that an officer is captured and has been taken hostage in a warzone. This warned others that they were to approach the captured individual and his captor with caution, and if necessary, to fire on their position when ordered.
Captain Dylan Hunt started to blink in morse code in order to indicate to Rommie, on board the Andromeda Ascendant, that there was an AC 145 in effect, when Bobby Jensen captured him on the Eureka Maru. ("Be All My Sins Remembered")