Annotations can be assigned to categories, corresponding to different groups of configuration settings. For example, annotations in different categories can be displayed in different colors. Additionally, categories are used in the Javascript API.

Categorizing configuration parameters is a two step process. First, annotations in the RSS file need to be assigned categories. <dc:subject> can be used in RSS 1.0, 2.0, and Atom. Be sure to include the xmlns:dc="" declaration in the root node. Alternatively, <category> can be used in RSS 2.0.

Here's a sample RSS 2.0 item, categorized with <dc:subject>.

 <title>An example annotation</title>
 <description>Just an example</description>
 <georss:point>26.58 -97.83</georss:point>
Then, configuration options need to be categorized. Add subtags to configuration parameters, with the node name as the Category and the node value as the associated configuration value.

For example, the following assigns different plotshape's depending on category. Any annotation not assigned to "category1" or "category2" will receive the default value, here "square".

The following configuration options are categorizable:
<icon>, <initialplotcolor>, <plotshape>, <plotsize>, <restingplotcolor>, <activatecolor>, <window>, <linecolor>, <linealpha>, <linethickness>, <fillalpha>, <zoomto>, <visible>.
Multiple Categories
It is possible to assign an annotation to multiple categories, to independently control multiple configuration options. For example, in a plot of recent earthquake activity, the size could vary according to the mangitude of the earthquake, and the color could vary according to how recently it occurred.
 <title>San Francisco Earthquake</title>
 <georss:point>26.58 -97.83</georss:point>


Categories and Tracks
The concept of categorized <track> display works slightly different. If the config option <trackcats> is set to "true" (as well as <track>) then lines are drawn between successive points belonging to the same category.

For example, say there are three successive points listed in RSS. The first and third are assigned "category1", and the second "category2". Without <trackcats>, the track line is drawn to connect all three; with <trackcats>, the track line is drawn between only the first and third.

Also note, <trackcats> ignores multiple categories; only the first, primary category is considered.