Apple Numbers '08 - Manual (Page 100)

100 Chapter 6 Using Charts
When you select a chart, the cells plotted in it are highlighted in the related table. In
addition, colored squares appear next to columns and rows in the table to show which
color represents each data series in the chart.
A button in the upper left of the table lets you switch between using columns and
rows as data series.
You can also click a series element in the chart to view its related data in the chart and
the underlying table.
Click this button to change
the chart orientation.
These squares indicate
which color represents
each data series.
When the button looks like this,
the columns are data series.
Click the button to make rows
the data series. When the button looks like this,
the rows are data series. Click
the button to make columns
the data series.
Selecting a bar highlights
bars in the chart in the
same data series as well as
related values in the
underlying table.