Algorithm 1. Identify positions.

1. Procedure: identify_positions of the modified data

2. Start

3. Input: The data class Ci in the data stream DS, the Morton Filter MF, Stack TK, counter i.

4. DS ← ø ; initial (MF), initial (TK);

5. i ← 0

6. while Ci ← DS.chkcls ( ) do

7. i++;

8. switch Ci.type do

9. Case “ €”

10. h ← DS (Ci)

11. if MF.involve (DSi) = = false

12. then DS.push (h);

13. MF.inst (h);

14. Case “£”

15. If MF.lookup (DSi) = = true

16. then h ← DS.pop ( );

17. MF.del (h);

18. Case “Data”

19. If detect (Ci) = = true

20. then Temp_DS = peek (TK)

21. if MF.involve (Temp_D) = = true

22. then

23. Dj = stacktraceback ( );

24. MPS = MPS ∪ {Dj}

25. End

Output: The set of modified positions MPS and modified data is detected.