Note: this option is not available for charts used in section reports.
Note: if you are using a time series chart you will also have the option to select the display type, demonstrated here with the Left Panel option.
The result is the option for the user to select which series they are viewing on the chart itself, as shown:
Series Selection Types
Single Series Display
If you are using a chart type that only has the capacity to display one metric at a time, such as a pie, you will have a drop down list appear at the bottom of your chart, as shown here.
Multiple Series Display
If you have selected a chart type that is compatible with multiple metric display, such as a bar or line, the result will be check boxes, as below.
Time Series Display
If you are using a time series label, you will be able to choose from a standard series selection display (as above), or a panel display, shown below.