From book:
“I’ve named this heel The Skinny Ankle Heel. It’s similar to a commercial heel and a neat fit if your slim ankles. Work the foot of the sock until you can just see the web between your big toe and second toe when you try it on.

“Note Socks are worked back and forth in rows on straight needles from cast on edge to beginning of heel, then joined and worked on DPNs to end.”