nbsCohpmRunningMaxNetBERexp is read-only and holds a cumulative statistic since the port was last configured (i.e. since boot-up or the last protocol/FEC/preference change) for the maximum network bit error rate (BER) on this coherent optical interface: it is the exponent half of a scientific-notation BER value, paired with the matching nbsCohpmRunningMaxNetBERsig object, where the true bit error rate is nbsCohpmRunningMaxNetBERsig x 10^nbsCohpmRunningMaxNetBERexp. A sysadmin reads it together with nbsCohpmRunningMaxNetBERsig 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.