To see the unique values that are active in your alerts table, click 
to open the Unique Values slider.
When you filter the alerts table by risk, assignee, origin, or rule name, the unique values in these categories are automatically updated. The unique distinguishers for the filtered alerts are also shown. A distinguisher is a field in an event, typically an IP address or hostname. For more information on distinguishers, see About distinguishers.
You can suppress or close all the alerts in each category. Click 
and select the required option. For more information on suppressing alerts, see Suppressing alerts. For more information on closing alerts, see Closing and reopening alerts.