The red flag with a diagonal white stripe from the upper mast to the lower outer corner was originally specifically for divers in the United States. The flag is not an official flag in that it is not part of the International Code of Signals Flags. Therefore a person acquiring a Captain's License does not have to memorize the meaning of the "Divers' Down Flag" but does have to know the Apfa flag means divers are in the water. It is the most common flag flown by divers in the USA. It is now used in many areas of the world and may be flown with the Alfa flag. It generally means there are divers within a specified number of feet from the flag. Exactly what legal requirements are connected with the use of the flag is determined by the law in each State. In New York State, Section 45, 1a of the State Navigation Law states that unless you are the vessel that is involved in diving operations, boats must stay at least 100' away from the flag.