The paint surface to the right of the arrows was reconstructed by a restorer after the painting was lined. During this lining the tacking edges were folded flat and then folded back again, resulting in paint losses around all the edges of the composition. In this detail you can see remnants of red paint along the edges of the two small white fields (indicated by the arrows). Mondrian had painted these fields red at some point before making them white. You can see more red traces in this area in a detail from the tacking edge ( next screen).