Thank you very much Michael.

Your code seems to be just what is needed.
I'll try it out after work.
The two selection points need to be on a 2d plane.
The plane needs to be addressable in x and y coordinates, in order to plot the curve created with points
derived by mathematics with x and y values, which I guess is what the var cplane = pointpicker.ptframe; does.
I do not know why it did not work with the Right view.

Or maybe I can set a frame on the 2d plane?

I think that the catenary curve could also be done this way...

- Brian