Lynn thank you for pointing us to the link Working the Heel of a Sock. I now understand that concept better and see that it isn't that difficult, however, I did not hear any mention of what proportion of the stitches are used for the flap. Is it half of the stitches or some other amount? How do you determine how many rows are needed for the flap before starting the gusset area? Are heel flaps only done on top down socks or can they be done on toe up socks?
Thank you and everyone else for all the help you so freely share.