Int 21 Fn 71AA  - Windows95 - Long Filename - Terminate Subst              [D]

   AX = 71AAh
   BH = 01h
   BL = drive number (01h = A:, etc.)

Return: CF clear if successful
   CF set on error
       AX = error code (see #1366)
       7100h if function not supported

Note:  the specified drive number may not be 00h (default), and presumably not
     the current drive either

See Also: AX=71AAh/BH=00h,AX=71AAh/BH=02h,INT 2F/AX=1000h,#1329