1 2 3 4 5 6

E E E E E E

* t X X X t

  * X X t X

    * t X t

      * t X

        * X

          *

handedness 1 2 3 R

handedness 2 3 4 R

handedness 3 4 5 L

handedness 4 5 6 R

handedness 5 6 1 R

handedness 6 1 2 L

sheetS 1 2 3 4 5 6