Pratique is the license given to a ship to enter port on assurance from the captain to convince the authorities that he/she is free from contagious disease. The clearance granted is commonly referred to as Free Pratique.
A ship can signal a request for "Pratique" by flying a solid yellow square-shaped flag. This yellow flag is the Q flag in the set of International maritime signal flags.
This article incorporates text from the public domain 1907 edition of The Nuttall Encyclopædia.