nbsCoherentStatsMaxNetBERexp is read-only and holds the maximum network bit error rate (BER) observed on this coherent optical interface since statistics collection last started or was cleared (nbsCoherentStatsState); it is the exponent half of a scientific-notation BER value, paired with the matching nbsCoherentStatsMaxNetBERsig object, where the true bit error rate is nbsCoherentStatsMaxNetBERsig x 10^nbsCoherentStatsMaxNetBERexp. A sysadmin reads it together with nbsCoherentStatsMaxNetBERsig to get the actual BER (sig x 10^exp) for the whole collection span reported by nbsCoherentStatsSpan, which is useful as a long-run health figure for this specific optic rather than just the current 15-minute/24-hour bucket.