Comment 5 for bug 255157

    attached are some demo files (.dxf) showing a comparison of the two types of spline. They were produced by typing a spline into Inkscape and outputting it as .dxf using both options, and then splicing the two .dxf files together to superimpose the images. In each case there will be two splines which will cross each other at two internal points (or more). One of the splines (ROBO) will have zero curvature at the endpoints. The agreement between the two splines is best for the case of a symmetric curve, presumably because the curvature at the endpoints is less in this case, for the original Bezier spline.
    if you load these into QCad, and try to edit them, the Bezier spline will display 4 control points, and the ROBO spline will show 6 control points. Of the 6 points, the first 3 and the last 3 will be collinear, which is a reflection of the property that the curvature is zero.
     if you load these into ROBO Master and try to edit them, then the Bezier spline will cause a crash, and the ROBO spline will display two internal fit points, which will apear at the crossover of the two curves, and will be editable with (hopefully) no unexpected consequences.