Originally Posted by
cadman
The square markers are to indicate what geometry feature you want to start on (white square) and what geometry feature you want to end on (black square). The round markers are what point on that geometry feature you want to start (white round) and end (black round).
If you have a contour made up of 500 arcs, lines and splines but you only want a toolpath along ten of those geometry features you would click on the piece of geometry you want to start on to set the first marker, then drag the black square marker to the geometry feature you want to end on. Then place the round markers where you want to start and stop. Also, you can right click on the round markers to explicitly set an additional distance to enter and exit.