This counts High Correction Count Seconds at the OTU layer: seconds during which the FEC correction rate itself exceeded a defined threshold, per the MIB's description. HCCS is effectively an early-warning counter for this specific OTU section -- it flags the seconds where FEC had to work unusually hard even though it still succeeded, which is often the first measurable sign of eroding link margin (aging amplifier, rising loss) well before the fault becomes visible as SES or SEFS; this particular bin is a live counter that keeps accumulating until it is explicitly cleared rather than rolling over on a fixed 15-minute or 24-hour schedule, so a large value mostly reflects how long it has been since the last clear. Seeing 2 high-correction-count seconds in this bin, especially if it recurs bin after bin, would prompt an admin to pull optical power and pre-FEC BER trends for this same port rather than wait for a hard alarm.