This read-write Gauge reports the number of bit errors detected in the received monitoring test pattern, updated once per second, capped at 99,999, and frozen (not incremented) whenever pattern synchronization is lost; writing any value to it resets the counter to zero. Admins use it to quantify how bad a DS1 line's error rate is during an active monitor test, and reset it before starting a fresh measurement window. An admin isolating a marginal T1 circuit would zero this counter, let the monitor run for a fixed interval, then read back the accumulated error count to gauge line quality.