Int 2F Fn DF01  U - Msg.com - Installation Check                           [N]

   AX = DF01h
   BX = 0000h

Return: AX = FDFFh if installed
      BX = segment of resident code
Program: MSG.COM is a TSR for intercepting incoming Novell broadcast
     messages written by Gary Dobbins (Dobbins@Arizona.Edu)