A tester that runs out of range records its rail instead of a reading. Here a handful of dies on Idsat hit the tester's 100 mA compliance clamp, and a few on Ioff read the open-circuit rail. Each is a number in the data and not a measurement. validLow / validHigh on the TestDef state the range a real measurement lies in, and valueFilter chooses which limit set a value must lie inside: validity (the default) drops the clamps; none keeps everything, and shows what a clamp does to the colour scale and the statistics. test and spec keep only values inside those limits. Bins and each die's recorded verdict are the tester's own, so yield does not move. Open the Summary panel for the Excl. column, or hover a grey die for the excluded value.