Int 21 Fn 5F01  - DOS 3.1+ Network - Set Redirection Mode                  [D]

   AX = 5F01h
   BL = redirection type
       03h printer
       04h disk drive
   BH = redirection state
       00h off
       01h on

Return: CF set on error
       AX = error code (see AH=59h)
   CF clear if successful

Notes: when redirection is off, the local device (if any) rather than the
     remote device is used
   calls INT 2F/AX=111Eh with AX on top of the stack

See Also: AX=5F00h,INT 2F/AX=111Eh