| The arrow is referenced -- perhaps with better detail on page 89 where you have the introduction to the Curves. Because of the short page count for the book, and advanced nature, this is the type of thing that will not be repeated as you go through the book...and regretfully I don't know that 'double-headed arrow' is going to make it clearer for everyone. However, see if the full description on 89 is helpful.
Let me know. |