This defines the offset direction of working parallelograms by stating the facing direction of the lonesome ends. Thus, from an offset parallelogram (e.g. after centers Counter rotate 1/4 and ends Hinge from a column):

Outrigger waves (Swing Thru) would require the very ends take adjacent centers ahead to form momentary parallelograms with the ends facing Out and do the indicated call (Swing Thru), then new ends and adjacents would recover (back up) to original footprints.

Inrigger lines (Mix) would require the very ends take adjacent centers backwards to form parallelograms with the ends facing In and do the indicated call (Mix) and then recover to original footprints.