I noticed an interesting detail on the 1926 Gottfrid Söderman lute that I'm currently working on. I think I've seen the same thing on other Söderman lutes, but didn't think too much about it. After some pondering, I think I found a reason why he cut two notches in the top just inside the edge of the fretboard. There must be a way to try and steer the almost inevitable crack in the top at the side of the fretboard to the underside of the fretboard where it is not visible. A bit like sweeping it under the rug. Gottfrid was an inventive autodidact, such a solution would be completely in his style. If that's not the reason, I have no idea why he did that!

You can see it did work on the normal straight edge of the fretboard, the crack came in the cut-out trench. However, it did not work at all on the side of the fretboard that is beveled.