Typically, the default data symbol in a layout is the most appropriate one to use and can be customized by modifying its properties in the Object Inspector. A bar chart has horizontal value bars; a candlestick chart has candlesticks.
However, you might want to create a second data layer on a particular chart. For example, you might want to display particular event instances on a timeline chart that tracks a continuous trend in the market. By adding an event band data symbol in a data layer, you can add depth and significance to a timeline chart.
You might want to use multiple objects for each data point. For example, you might want to display a company name above each point in a scatter chart. To do so, you can add a text object above the point object in the data template. The data symbol is then a point and a text label.
If you create a multiple-object data symbol for a chart with axes that are measured data units instead of inches (or metric units), you should use an alignment panel to prevent the data symbol objects from overlapping.
Typically, when a layout requires an alignment panel to group objects at each data point, the data template includes the alignment panel for your convenience. For example, the X-Y chart has axes mapped to column values and includes an alignment panel so you can easily add other objects to represent data points.
When you use an alignment panel to group data symbol objects, a panel is centered at each data point. To determine to what you should set the Location property for an alignment panel to, look at the Location property of the default data symbol for that chart. For charts with axes that supply an alignment panel by default, the Location property for alignment panels is set to the Pt() function, which references one or more column names.
The following figure illustrates an alignment panel with child objects in the World Manager.