Sport mirrors
Sorry, I didn't get back to this thread until today. No, this measurement is taken from the point farther forward to the front of the door. Follow right along the "sharp" edge of the door top (right where the top rolls over and begins the vertical side of the door skin). It's where you can actually hook the end of your tape measure. If I still don't make sense to you, I can take another pic with a tape measure in place.
Let me know,
Jerry