INT 2F - NETWORK REDIRECTOR (DOS 3.x only) - LOCK REGION OF FILE

	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 #01680 at INT 21/AH=59h/BX=0000h)
	STACK unchanged
Notes:	this function is called by the DOS 3.10-3.31 kernel
	the redirector is expected to resolve lock conflicts
SeeAlso: AX=110Bh,INT 21/AH=5Ch