This flag indicates whether the historical one-day performance data for this interval is valid or should be disregarded. An admin checks this before trusting a historical day's packet or octet totals, since a false(2) flag means that day's data was compromised, for instance by a partial outage. For example, a day where the device was down for maintenance for several hours might have this flag reported as false(2), warning the admin not to use it in a monthly average.