Tenoning in progress. The rabbet bit just walks around the work and creates a face and a shoulder simultaneously, all in the same plane. Plunge the router to lengthen the tenon. A PC 7529 plunger is shown here with an oak ski. If the ski is twice as long as the window it cannot dip into it.
Longer stock is clamped in a vise and the jig is clamped to to the work.