From Nancy Bush’s pattern description:

The Child’s French Sock was originally designed for a little girl of two or three years. It has a very interesting pattern and seems perfect worked in a larger size for a grown-up. I have stayed faithful to the pattern, except that I’ve used slipped stitches along the sides of the heel flap. To do so, I’ve had to pick up a few more stitches than there were slipped stitches available. This sock has a French Heel and a Flat Toe.