Maximum Corner Angle
The maximum corner angle is computed as follows.
The maximum angle between adjacent edges is computed using corner node positions in 3D space. (Midside nodes, if any, are ignored.) The best possible triangle maximum angle, for an equilateral triangle, is 60 degrees. The figure below shows triangles having maximum corner angles of 60 degrees and 165 degrees.
The best possible quadrilateral maximum angle, for a flat rectangle, is 90 degrees. The figure below shows quadrilaterals having maximum corner angles of 90 degrees, 140 degrees, and 180 degrees.