This counter measures the cumulative far-end errored seconds from midnight to now as reported by the remote DS1 equipment. A network engineer uses this to perform end-to-end SLA calculations and to identify whether error accumulation is happening uniformly across the day or in specific periods. For example, if far-end ES is 200 by 6 PM, combined with local ES of 150, you have a network-wide quality problem that needs both facilities to investigate.