Gauges do not use PopChart XML's GraphData element. Instead, you set the value and ranges of the gauge in its Graph element.
To set a gauge's data value, label, and minimum/maximum values, you should use the Values subelement in Graph. The Values subelement contains these attributes: Value, Text, Minimum, and Maximum. For each range in the graph, your Graph element should have a separate ColorRange subelement. The ColorRange subelement has the following attributes: Name, Color, Minimum, and Maximum.
Example 12.16 illustrates how a Graph element for a gauge would look in PopChart XML.