The Commanding Officer has the ultimate responsibility for the safety and well being of his ship and crew and to ensure that the ship's current mission is being satisfactorily executed. The CO's immediate staff are the First Officer and the chiefs of the other departments (the Department Heads), but is, in reality, the entire ship's complement. The CO has no set duty shift and is always considered to be on call. On larger starships the CO usually has his own office, and this office is sometimes very close to the bridge, offering quick and easy access in emergency situations. The CO is also responsible for meting out punishment for crewmembers found guilty of breaking major regulations. The Commanding Officer is also traditionally the member of the crew who performs such duties as marrying crewmembers under his command and serving as the host at all official functions held aboard his ship.