RNS Regulations require that all officers of the watch give orders in the "customary phraseology of the service." This is not merely a matter of preserving tradition but of ensuring that orders are clearly understood and promptly obeyed. For example, when the officer conning the ship gives an order to change engine speed, he begins with which engine to change (starboard, port, or all), whether forward or back, and by how much (flank, full, one-third, etc.). An engine order might thus be given "Starboard ahead one-third, port back one-third;" the lee helmsman, who operates the engine order telegraph that sends the instructions to the engine room, repeats the order, adding "aye aye, sir (or ma'am)."