Generating Reports off Categories field

Hello - The OO user guide indicates that there are reporting metrics available via searching for a Category.

I'd like more details on how to generate reports based on Categories and ROI.  Thanks

 This is the reference in the User Guide:

"Users might use categories to create reports that indicate the health of key infrastructure components. For example, if you assign the category Server to all the flows that check server health, then a report that finds only flows that were assigned the Server category could highlight the health of the servers on your network. You can also use categories for filtering a search. For example, you can run a search that only looks for flows that have the Security category. Categories are stored in the Configuration\Categories folder. "