INT 7F - Alloy NTNX, MW386 - GET NTNX FILE MODE
        AH = 26h
        CL = 00h
Return: AX = file mode bits
            bit 0: directory protection enabled
                1: extended open enabled
                2: flush on every disk write
                3: flush on every disk write in locked interval
                4: flush on reads from simultaneously opened file
Note:   MW386 does not support file modes, and always returns AX=001Fh
SeeAlso: AH=26h/CL=06h