 Although the United States Coast Guard has its own service ensign, all other U.S. Government ships fly the national ensign their service ensign, following United States Navy practice.To distinguish themselves from ships of the Navy, such ships historically have flown their parent organisation's flag from a forward mast as a distinguishing mark.Today, for example, commissioned ships of the National Oceanic and Atmospheric Administration (NOAA) fly the NOAA flag as a distinguishing mark.