csDs3Ds1TotalUASs is a read-only PerfTotalCount counter reporting the number of Unavailable Seconds — seconds counted once ten consecutive severely errored seconds occur on the DS1 — that this channelized DS1 (T1) circuit carried inside the DS3 has recorded summed across the entire previous 24-hour period, with any invalid 15-minute bucket counted as zero. A rising count here is the operational signal that an extended outage of that individual T1 channel is happening on that interface, which is exactly the kind of degradation a monitoring admin wants an early warning of before it causes an outage. For example, comparing csDs3Ds1TotalUASs's 24-hour rollup from one night to the next lets an admin judge whether an extended outage of that individual T1 channel on this channelized DS1 (T1) circuit carried inside the DS3 is a one-off blip or a worsening trend.