I followed the p.133 Exercise 53 (Control Point.3dm).
When I lofted the surface with which I was to discover that seams were created and therefore control point editing could not be turned on, I found that my lofted surface differed from the one in the guide. My surface edges did not strictly adhere to the curves, ie did not go fully to the pointy control points, therefore did not create seams therefore I could turn on points.
I have looked at tolerances but this does not seem to be the problem. I tried all the options in the Loft Surfaces dialogue box.
What setting does this appertain to? Thank you