Throughout history and every war there have been those who were classified as Missing in Action (MIA). Wikipedia gives this definition in the opening lines of the article on MIA. "Missing in action (MIA) is a casualty classification assigned to armed services personnel and other combatants who are reported missing during wartime. They may have been killed, wounded, become a prisoner of war, or deserted." This is a very well rounded statement describing exactly what is meant by MIA.
