This read-only value is the current-interval count of P-bit Severely Errored Seconds, seconds with a high enough density of P-bit errors to be classified as severe, applicable only for DS3. Severely errored seconds indicate more serious, potentially service-affecting degradation than ordinary errored seconds. For example, an admin treats a nonzero csDs3StatCurrentPSESs count as more urgent than a rise in plain PESs, since it implies periods of significant, not just occasional, parity errors.