any one can tell me why we r supposed to use pis x(2) for file status instead of 9(2).
As Muthuvel pointed in his url:
If status-key-1 is a nine (9) then status key 2 is "implementor-defined". Many vendors take advantage of the x"00' to x'FF' (or 0-255) binary value. Therefore, the file status key may not always be a numeric value.