Int 2F Fn 110B  CU - Network Redirector (dos 3.x Only) - Unlock Region Of  [N]

   AX = 110Bh
   BX = file handle
   CX:DX = starting offset
   SI = high word of size
   STACK: WORD low word of size
   ES:DI -> SFT for file
       SFT DPB field -> DPB of drive containing file

Return: CF set on error
      AL = DOS error code (see #1366 at INT 21/AH=59h/BX=0000h)
   STACK unchanged

Note:  this function is called by the DOS 3.1-3.31 kernel; DOS 4.0+ calls
     AX=110Ah instead

See Also: AX=110Ah,INT 21/AH=5Ch