I am almost hesitant to post this,because i dont want to seem like a know it all or argumentative,But,in the interest of the newbies on the site,i feel we should get the proper terms down,as to not confuse people.Spine,is how much bend their is of a shaft,when measured for Paradox.Spline,is the reinforcement,in the nock area of the arrow.Otherwise known as a insert.