question from page 50 in the book Two-piece Front CT.04
After creating points 13, 13A & 14 there is a line of text that says
" Find point to point measure from pt0 - pt13a and double."
It doesn't say what this computation is used for?
Will it be used later?
It goes on to create points 15,16 etc.
What am I missing here?

Rory answered my question and the patterns include the wearing ease! Next challenge for me is a jacket. Going for the the Two-piece Front