Nice, what does the yellow line mean ?
Else, to answer to your colleague, in “orange” is what OpenCutList will detect as “arcs”.
Unfortunatly this doesn’t work directly with his example. Because of a small edge that cut the curve. Those edges should be removed and top a bottom edges of the face recreated.
My algorithm convert segments to arc if at least 6 consecutive points are located on the same ellipse.
As you can see, the result DXF is no longer polyline (because polylines can’t contains ellipses). It just successive lines and portions of ellipses.
table-top.dxf (10,1 Ko)