Int 6F Fn 08  - 10net - Unlock Handle                                      [N]

   AH = 08h
   BX = file handle
   AL = mode
       00h unlock all
       01h unlock record at CX:DX

Return: CF clear if successful
   CF set on error
       AX = error code (see also AH=00h)
       0002h file not found

See Also: AH=07h,AH=0Fh,INT 21/AH=5Ch