Insertion Wave Stitch
A variation of Wave Stitch Filling. Designed by Jacqueline Enthoven (The Stitches of Creative Embroidery, 1964) to embellish (and hide) the seam created when adding adding material to lenghten a skirt or dress. Her method of having the joined seam open on the outside of the garment, and then using Wave Stitch Filling and a trim over it, is a very clever way of making the garment neat and on both sides.
The Stitches of Creative Embroidery, 88