|BNSF 7214 sits in front of the former AT&SF railway depot in San Bernardino for National Train Day. The sign is referred to as a "Blue Flag" and is placed on on the track, or the engine, or car that is the subject of the flag. A blue flag keeps the item, or train from moving and can only be removed by the person, or a person from the craft that placed it. Once someone places a blue flag on the track, it is quite safe to stand on it since nothing is going to move on that track until the flag is removed. Blue flags can also be hung on the side of the train, stuck in the coupler, or a blue light or lantern may also be used. -Craft is a rail term referring to the department that a person belongs to, whether it be the car fixers (car dept.) or the track workers (MOW) or the train crews and yard people (TE&Y).