As stated in the description, this is the cleared time of the bin -- the timestamp of the last reset of this row's counters. On a closed Hist24H row, comparing this to StartTime and Duration tells you whether the counts alongside it cover the bin's full normal interval or were cut short by a manual clear partway through. For example, a ClearTime of '2024-03-13,00:00:00.0' sitting well before the current time, with steadily climbing counters in the same row, tells you those totals reflect a long, uninterrupted accumulation rather than a recent reset.