state  |  event X  |  event Y  |  event Z
-------+-----------+-----------+-----------
  A    |     B     |    C      |    E
-------+-----------+-----------+-----------
  B    |     D     |    -      |    E
-------+-----------+-----------+-----------
  C    |     E     |    -      |    -
-------+-----------+-----------+-----------
       |           |           |

... etc.

       |           |           |
-------+-----------+-----------+-----------
  E    |     -     |     -     |    B
-------+-----------+-----------+-----------