Oh! I see. This is a variation on a technique that I saw on a DVD of sandra Betzina. After you've created a bound buttonhole you bold the lips back over and sew them together leaving the buttonhole part open. Sandra Betzina does this with an extension piece. On the center front of a blouse you add the extension and you leave open the places for the button.

this is pretty confusing to follow from the directions and the photos.

What a fantastic use of stripes! It's amazing. It has a great look that's timeless and hints at naval origins.