For Mortising, The WoodRat employs a shop-made rail that clamps onto the sliding bar. Your piece for the mortise is clamped onto this rail.

Here the PlungeBar is used to drill a row of neat holes. Then track those holes through the bit to join them up as a slot mortise. This function can also be used to make dowel joints or to cut accurately depthed recesses for locks and hinges.