Gavin, I have good news .... Dongjin, ADN, added: Math.Round(val, 10, MidpointRounding.AwayFromZero) to ALL of the input parms to DirectPositionImpl (I had not done this for dpi_center on the aCircArcSeg = fgf.CreateCircularArcSegment(dpi_start, dpi_center, dpi_end) call. All of my test cases now work ...! dennis