From:  Michael Gibson
3139.11 In reply to 3139.10 
Hi Burr,

> I was actually just responding to a guy in another forum who
> is having difficulty with "Corel Type" geometry in a
> Cad/CAM software.

That may actually be due to a different problem yet.

One other thing that is not too unusual with 2D drawing programs is to make one of those 4 point curve segments be set up with the first 2 points stacked up right on top of one another.

That somewhat degrades the mathematics that is operating behind the curve definitions, and that kind of "stacked up" / duplicated points can cause problems with various CAD/CAM programs that want to do some more sophisticated processing of the curves.

It may be due to a choice by the user making the 2D drawing data to use a particular node type on the starting node of a curve like "collapsed start" or "collapsed end" maybe something like that. They might want to avoid that kind of node type and instead make sure they have a visible tangent handle on every spot.

- Michael