The engineering chart can be used to compare data from a single point across different date ranges.

Clicking the above checkbox enables the ‘Comparison Start’ field.

Leaving the graph with its default date range and setting the comparison start to one year earlier.

Clicking the refresh button gives:

We now have two traces and two x-axes. Note the two names in the legend; the © at the end of the second one indicates that this is the comparison line.

The remaining menu options are dealt with in later sections.