Alerts are automatically cleared once the condition causing them clears and may be ‘Snoozed’ for a specific period of time to avoid new alerts during that period.
However, some alerts have no mechanism to automatically clear because the alert signals an event more than a problem condition.
A manual CLEAR action would manually change the state to OK so that all future events would be caught as another state change. Alerts that are automatically cleared would continue to be automatically cleared as they are currently.