As you can see from the PDF SNA1_1_for_Rubq that I've sent offline, I'm getting the hang of the plotting now.
Unfortunately, now that I see how to do it, I also see that for S,N,a1,1 and regression c on (e,u,u*e,u^2), no term is "good" except u^2. The PDF shows this clearly because only for u^2 does the "line of interest" put any distance between itself and "the pack".
Well,I will do all of them and we will see what we will see ...
Thanks again for showing me the technique ... much appreciated.