The correct terminology is as follows, the back of the bow is the side of the bow that faces what you are shooting at, the face of the bow is the side of the bow you see when you draw. To measure "Traditional Draw", which is what most of us use, you should measure from the back of the bow, to the point of anchor.
For "True Draw", and Jennings Archery was the only company that I have ever known to use this method, is measured from the sight window on the face of the bow to the point of anchor.
I hope I cleared it up for you. As stated above, please leave additional length for broadhead.