This attribute indicates the total number of one second intervals for which the DS3 path is unavailable. The DS3 path becomes unavailable at the onset of 10 consecutive C-Bit Severely Errored Seconds (CSES). The 10 CSESs are included in the unavailable time. Once unavailable, the DS3 path becomes available at the onset of 10 contiguous seconds with no CSES. The 10 seconds with no CSES are excluded from the unavailable time. For second intervals where CUAS is counted, counting of C-Bit Coding Violations (CCV), C-Bit Errored Seconds (CES) and C-Bit Severely Errored Seconds (CSES) is inhibited.