Demonfox,

Thank you for your suggestion, I think that is an excellent approach. I don't anticipate we keep every version of the data as it is very expensive to do so, but it is likely that user wants to have several versions of the data instead of just one, though it is unlikely user will go beyond the 1 version.

If you can think of other approach please do post again as i do have sometime to find the best approach I can find for this.

Again thank you for your suggestion

Regards