INT 6F - 10NET - UNLOCK HANDLE                                                  
	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
SeeAlso: AH=07h,AH=0Fh,INT 21/AH=5Ch