fig5 b corner rounding takes the form of a smooth curve such a shape is difficult or impossible for conventional eda software to handle the corner may be approximated with a sequence of straight edges in a u201c polygonal u201d approximation a compromise may be found between the simplicity of such a polygon and the precision with which it approximates the ideal curved figure the inventors have found a single diagonal edge with symmetrical 45 degree angles at each end to be a good compromise in most cases restricting the geometry to edges at angles that are multiples of 45 degrees has practical advantages in mask making because most mask writing machines must approximate other angles using a u201c stairstep u201d pattern however it shall be understood that a larger number of diagonal edges and in some cases an angle other than 45 degrees can better approximate the true corner rounding and may be preferred in particular situations assuming the case of a single chamfering edge without restricting its angle the chamfer cutout would be a triangle chosen so that one of its legs equals the short overlap o s and the other equals the long overlap o l the values of e s and e l which are necessary to define a serif are ignored when creating this chamfer o s and o l normally differ in length because of differences in the lengths of the two original target edges with the.