- a yellow flag, designating the letter Q in the International Code of Signals: flown by itself to signify that a ship has no disease on board and requests a pratique, or flown with another flag to signify that there is disease on board ship.
- the yellow signal flag for the letter Q, flown alone from a vessel to indicate that there is no disease aboard and to request pratique or, with a second signal flag, to indicate that there is disease aboard
