Per its DESCRIPTION, this Counter64 counts seconds declared unavailable based on the P-bit performance parameter rather than the line-side counters. Because this row is the short interval still actively filling right now, a reading here means the DS3 circuit was declared unavailable specifically per the P-bit (far-end) measurement, not the line counters on this DS3 circuit, and because the interval has not closed yet, the count will keep climbing until it does and rolls into the history table. For example, a reading of 4 seconds in this bin on this DS3 circuit even while the line-side Uas equivalent stays at zero tells you the far end declared an outage that the near end circuitry did not itself detect.