Changes made during a session will be replaced with the original data.

It uses the original data so they don't lose any.

This is significant especially where the original data was produced on technology at a lower level than currently possible.

This copy can be used when the original data is changed, or lost.

The result will be the complement of the original data.

The original data for the 1890 Census is no longer available.

Case 2 - to suggest some candidates where none was found from the original data.

It would explain why the original data had never been destroyed.

She happened on the original data for some of the experiments reported in the Cell paper.

No one felt a need to go back and examine the original raw data.