This read-only Unsigned32, in frames (0 to 4294967293), defines how many frame errors must occur within the cienaCesOamErrFramePeriodWindow to trigger an Errored Frame Period Event, per its description, defaulting to a highly sensitive setting of just one frame error. Because the default threshold is so low, this event type will fire on almost any single bit error within the measurement window, making it one of the more chatty OAM alarms unless explicitly tuned upward for a link known to have some baseline error rate. An engineer seeing frequent Errored Frame Period events on an otherwise acceptable link might deliberately raise this threshold above the default of 1 to reduce alarm noise.