Here are a couple of good links explaining Correctables and Uncorrectables. While both of these links tend to focus on the Upstream, the principle is the same on the downstream.
Downstream Correctables and Uncorrectables both have data corrupted by noise on the downstream but the difference is that the corruption is less in a Correctable so it can be fixed with FEC(Forward Error Correction)
From the second article
Whats an acceptable percentage or number of codeword errors? Thats definitely an it depends question, but lets start with an ideal goal: No correctable or uncorrectable codeword errors at all in either the downstream or the upstream. One could argue that, in a network performing so well that there are no codeword errors of any kind in the QAM signals, it would be possible to take advantage of eliminating FEC overhead altogether and picking up a little more throughput per channel. Of course, this goal is unrealistic.
The percentage that is important is the number of uncorrectables to octets(codewords). Your percentage is very low. Of course the overall percentage can be misleading if something has suddenly gotten worse and prior data disguises the recent percentage.--
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