I think you may get a more accurate result if you avoid using the "REGION" keyword in your example. That way, only the edges corresponding to the depth of the notch will make it to the next step where you check the length. If you prefer the region style of output then it is still possible. You could use one step to create the regions for the external spacing check as you already are and another step to create edges for a similar external spacing check as I suggested. Once you find the edges that are too long you could select just the notch regions that have coincident edges with the edges that failed the length check. The WITH EDGE operation would be helpful for that last portion.