1 2 3 4
E E E E
* X X v
  * - c
    * t
      *
handedness 1 2 3 R
handedness 1 2 4 R
handedness 1 3 4 L
sheetS 2 4 3
sheetD 1 2
length 1 E 5 100
length 2 E 5 100
length 3 E 5 100
length 4 E 5 100