The category element represents any category that can be used to classify a topic for navigation or retrieval. Topics may belong to multiple categories. You may apply multiple categories to a topic, but each must use a separate instance of the annotation.
As an example, you may want to apply the categories "How To" and "Task" to all level 1 task topics. Here is how your rule may look:
Here is the output you would get from the rule above using our sample document.