drawing features?

Some early hand sketchs of some type designers have little lines on the outline of the characters, like this one of Jean François-Pochez (http://farm5.static.flickr.com/4147/5032761184_4c3f907cdc_b.jpg)

This little lines become nodes on the scanning process? Or what is the true function of them?


The little tick marks are related to Ikarus, the first system for creating digital outline fonts.

More info about Ikarus here.