The diagram shows the more geometrically rational designation of tailback behind the fullback. However, some would label the deepest back in this form of deuce backfield "HB", considering one halfback to have moved behind the fullback, who is in both the role of blocking back and the heavy up-the-middle runner. Those who would emphasize the blocking role of the FB (the "up back") might even label the deepest back, "RB", with a BB instead of FB. Few, however, would use the straightforwardly geometric labels of QB, HB, and FB in that order from front to back.