This counts the seconds during which this E1 port was considered available, i.e. not in the UAS state. Dividing AS by the bin's total time (TT) for this port gives the actual availability percentage an admin would report for this circuit over that window -- and this specific object covers a cumulative counter reset only by an explicit clear rather than on a fixed schedule -- reflecting everything since PM stats were last cleared. For example, since PM counters were last cleared, this E1 port might show this counter at 86000 -- a concrete count the admin can trend against neighboring bins to judge whether the condition it reflects is worsening.