This read-only Unsigned32 counts the number of errored seconds recorded since the BERT test started, per its description, i.e. seconds in which at least one bit error occurred. An administrator uses errored-seconds counts as a standard telecom line-quality metric that's often easier to compare against SLA thresholds than raw bit-error counts. For example, an operator reporting line quality to a customer might quote bertTestStreamMonRxESsSinceStart directly since many SLAs are defined in terms of errored seconds rather than bit error rate.