DUSTWUN (abbreviation for duty status—whereabouts unknown) is a transitory casualty status assigned to United States servicemembers who cannot be located but have not been confirmed, captured, or found dead. A servicemember can only stay in DUSTWUN status for ten days.
History
Private First Class Bowe Bergdahl is famous for leaving his Army post in Afghanistan in 2009, intending to hike about 20 miles to the closest command center, that triggered a "DUSTWUN" manhunt that lasted 45 days without success.
References
DUSTWUN Wikipedia(Text) CC BY-SA