Per its DESCRIPTION, this Counter64 counts one-second intervals where the DS3 P-bit error density crossed the severity threshold. Because this is a lifetime counter that only resets on an explicit clear, a reading here means P-bit-layer errors from the far end clustered badly enough in one second to count as severe on this DS3 circuit, accumulated over the port's entire service life, not merely since the last reboot. For example, a reading of 1 severely errored seconds here, rising in step with Pcv/Pes on the same row, points at a far-end framing problem rather than anything on the near-end line side.