This counts the total number of bits received during this port's BERT session, saturating (stopping) at 0xFFFFFFFF rather than wrapping around. Because it is a Gauge that saturates instead of a wrapping Counter, a long-running test on this specific channel can pin this value at its maximum well before the test actually ends, so an admin relying on it to compute a bit error rate needs to watch for that ceiling being hit rather than assume the value keeps accurately climbing. A 24-hour BERT at a T1 rate on this channel will accumulate well over 4 billion bits, meaning pportBertBitCount would saturate at 0xFFFFFFFF long before the test naturally completes, capping the usefulness of this counter for that run's full duration.