csOc3AtmCurrentCorrectedHEC is a read-only 64-bit counter of the number of ATM cells on this OC3 port whose Header Error Control byte contained a single-bit error that was automatically corrected. A steady trickle of corrected HEC errors is generally tolerable since the cell header was successfully repaired, but an admin watching this counter's rate climb is seeing early evidence of a marginal signal before it degrades into uncorrectable errors. For example, an admin who sees csOc3AtmCurrentCorrectedHEC climbing gradually over a week, even with csOc3AtmCurrentUnCorrectedHEC still at zero, would treat it as an early warning to inspect the fiber connector or transceiver before it gets worse.