System Variable , Alarm counts

System Variable , Alarm counts

Hi , knowing that we could create a few alarms counts for acknowledged alarm, unacknowledged alarm, total active alarms. 

1.Timing Issue
      a. May I know how this count based on?
      b. Which memory does it refer to?
      c. How do I suppose to know the time frame of the alarm?
      d. Could I set a time period for the count?

2. Data reset
      It is possible that I could reset the number of alarms count.  It is a read only variable, please suggest       method of resetting it.

Thank you.