This integer sets the Unavailable Seconds count that, if exceeded within the current 15-minute Line-layer interval, triggers a statistical alarm, defaulting to 10 and applying identically to near-end and far-end. An admin cares because UAS represents actual service-affecting downtime, so this threshold of 10 out of a possible 900 seconds in the interval is what decides how much real outage time is tolerated before an alarm fires on either direction of the line. For example, a far-end UAS count of 12 within one 15-minute interval would breach this threshold just as a near-end count of 12 would.