Corners points

 From:  Zooen
12121.1 
Hi Michael,
I’ve just come across something that’s puzzling me. When you offset a smooth curve with no corner points, the result is a curve with lots of corner points. However, if, for example, you extrude the curve, you don’t see any edges on the extruded surface.
Below is a small file to illustrate what I mean.

- Zooen