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

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

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

Notes: this function is called by the DOS 3.10-3.31 kernel
   the redirector is expected to resolve lock conflicts

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