The Detect main points function allows you to automatically detect the main points from the pieces created from curve points. Once this function is applied, the curve points with an angle value no greater than the value set in Settings (Technical / Detect main points through angle) are transformed to main points.
The function is useful for pieces that were digitized, or the pieces that are coming from DXF Standard import, PLT, or CUT. The function can be applied to a single piece or to a group of selected pieces.
The main points are also grading points and they are needed when grading the piece. For more information related to main points and curve points click on this link.