When you select the acknowledgment type No acknowledgement, the triggered alarm returns to normal state and disappears from the alarm view when the monitored variable no longer meets the criteria to trigger the alarm. You select this user action when the user only needs to see a status and does not need to take any action on the alarm, for example, to see if a space is occupied or not.
The user can acknowledge the alarm in the alarm view to let other users know that the alarm has been noted. The acknowledgment is optional and the alarm does not require an acknowledgement to return to normal state.