International Code Flag - Q

The Annin Yellow Quarantine QUEBEC Flag is no longer flown to indicate that a vessel is quarantined due to disease. The all yellow flag now has the opposite meaning. It is used to signal that a vessel is free of disease and is requesting boarding for inspection by Port Control, for the purpose of granting a Free Pratique.
The quarantine flag, also called the Yellow Jack, is the international signal flag LIMA, this is the official quarantine flag recognized by the World Health Organization (WHO). It is square in shape. Its display is divided into four smaller squares, with two on top and two on the bottom. The smaller squares are alternately yellow and black in color. The flag is flown from a ship that is either arriving in port with known serious health problems or that has been placed under quarantine by the local port authorities.

Once the local authorities have determined that the ship’s health problems have been resolved and removed the quarantine order, the ship may fly the free pratique flag (e.g., the international signal flag QUEBEC), which is solid yellow.