This unassuming little machine has been designed to cut the little ledges [picture on the right] for the bindings.
Binding does a couple of important things. the binding covers the end grain of the top wood. That is important because moisture wicks into that end grain very easily thus warping the top eventually.
Also the binding, which again is nothing more that a little stick, spans the gap between top and side making a very strong and secure connection.
Also, it can be made to look really cool as well. And, which will be the case here, the binding will make a visual transition between finishes, in this case the top and the sides will be different colors, and a clean break will be necessary.
This binding cut was the very first use for this new binding machine. And as is the case most of the time, simple works very well indeed.