Controls the look for circular gauges.
Example:
<circular>
<axis radius="50" start_angle="90" sweep_angle="180">
<scale minimum="0" maximum="120" major_interval="20" minor_interval="5" />
<scale_bar enabled="false" />
<labels enabled="true">
<font bold="true" />
<format>{%Value}{numDecimals:0} mph</format>
</labels>
<minor_tickmark enabled="false" />
<color_ranges>
<color_range start="0" end="40" color="Green" />
<color_range start="40" end="80" color="Yellow" />
<color_range start="80" end="120" color="Red" />
</color_ranges>
<custom_labels>
<custom_label value="65" enabled="true">
<label enabled="true" align="Outside" padding="20">
<format>Optimal</format>
</label>
<tickmark enabled="true" shape="Star5" auto_rotate="false" width="10" length="10" align="Inside" padding="12">
<fill color="Blue" />
<border color="DarkColor(Blue)" />
</tickmark>
</custom_label>
</custom_labels>
</axis>
</circular>