A "Code Yellow" signified a distress call from a starship utilized by the New Republic starting around 4 or 5 ABY.
Sometime around 4 or 5 ABY, the Victorum, an Imperial II-Class Star Destroyer that had been captured, transmitted a Code Yellow signal. This occurred because its hyperdrive malfunctioned, resulting in it being marooned within enemy territory. The Temperance received this signal and subsequently dispatched Vanguard Squadron to provide aid.