This value, from 1 to 96, identifies which of the past 24 hours' completed 15-minute intervals a row in the DS3 interval table represents, where 1 is the most recently completed interval and 96 is nearly a full day earlier. Admins use it to plot a 24-hour trend of DS3 line errors and unavailability by walking through the numbered intervals in order. For example, comparing ds3IntervalNumber 1 against ds3IntervalNumber 50 lets a technician see whether an error condition just started or has been present for hours.