This PmTcaUnsigned64 is the basis value plus the configured overflow threshold, per its DESCRIPTION, and a statistic reading at or above this boundary at the end of a sample interval registers an overflow condition, incrementing the overflow current count and potentially leading to an Adjustment TCA once that count reaches the configured OverflowCount. Unlike the slower Adjustment upper/lower boundaries, which are only evaluated once per Adjustment Interval, this boundary is checked every single sample interval, which is exactly why Overflow can catch a sudden spike and start counting toward a TCA long before the main Adjustment mechanism would even get a chance to look. For example, on a 5-minute sample interval, three consecutive samples above this boundary can trigger an overflow-based Adjustment TCA within 15 minutes, well before a 1-hour Adjustment Interval would have completed its first evaluation.