My Father volunteered to join the RN and did his training as a Engine Room Artificer in 1943. He was posted to HMS Lanka in Ceylon. what i can't understand on his documents were the letters in brackets (DEBM). As he was not attached, so it seems, to a particular ship what would he be doing there March 1944 to November 1945 and what was his job (DEBM)? Thank you to anyone as to clues.