This counter tracks Severely Errored Seconds accumulated at the Section layer over the current one-day interval, the daily rollup of the more serious SES metric. An admin cares because a high daily SES count, even with low counts in any single 15-minute window, reveals a persistent low-grade problem that could otherwise be missed by only checking the current 15-minute snapshot. For example, several SES events spread one per hour across the day would each look minor in isolation but sum to a daily SES count worth escalating.