Perfect for back-beveling. With the sander securely mounted and connected to the vacuum adapter (the long black tube to the left in the photos below), dedicated hardware (the knob above the vacuum adapter) makes quick work of attaching the fence. The slotted arm (whose knob is next to my right thumb) allows fence adjustment relative to the sanding belt and the curved slots at each end of the fence provide bevel settings.
A classic application for this kind of bevel is adjusting mitered door or window trim. If the wall around the opening isn’t flat, fastening can fold the casing backward, creating a gap. By undercutting the trim piece and adding a back-bevel, the joint closes to a tighter fit.