Hi, I just switched from mm to mils in my PCB layout, and now get hundreds of Via Diameter DRC errors. I'm pretty sure, I didn't set the required Via Diameter to be 24.016mils in the first place. The Via Diameter was originally specified to be 24 mils, and the Via is actually still 24 mils. It seems there's a rounding error in converting the DRC rules data, when switching the PCB from mm to mils. I would recommend to create DRC rules in both mm and mils, when defining them. So changing measuring unit, would not recalculate forth and back with resulting rounding errors. The entered value is set as specified, the alternative is calculated, and not calculated again, even when switching measuring unit, unless the value is later entered in the alternative measuring unit, in which case the first valus is then calculated.