Flag semaphore (from the Greek σῆμα, sema, meaning sign and φέρω, phero, meaning to bear; altogether the sign-bearer) is the telegraphy system conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags; it is read when the flag is in a fixed position. Semaphores were adopted and widely used (with hand-held flags replacing the mechanical arms of shutter semaphores) in the maritime world in the 19th century. It is still used during underway replenishment at sea...