nbsCohpmHistoricAveNetBERsig is read-only and holds a finalized statistic from a completed past reporting interval for the average network bit error rate (BER) on this coherent optical interface: it is the significand half of a scientific-notation BER value, paired with the matching nbsCohpmHistoricAveNetBERexp object, where the true bit error rate is nbsCohpmHistoricAveNetBERsig x 10^nbsCohpmHistoricAveNetBERexp. A sysadmin reads it together with nbsCohpmHistoricAveNetBERexp to get the actual BER (sig x 10^exp) for this reporting period, e.g. a sig of 5 and exp of -9 means a BER of 5x10^-9, and would compare it against the link's expected error-free threshold when troubleshooting marginal optical performance.