Complex spanning pattern (no edge knows all rows/cols):

+-----------+----------------------------------------------------+
| W/NW cell | N/NE cell                                          |
|           +-------------+--------------------------+-----------+
|           | W/NW center | N/NE center              | E/SE cell |
|           |             +------------+-------------+           |
|           |             | +--------+ | E/SE center |           |
|           |             | | Middle | |             |           |
|           |             | | table  | |             |           |
|           |             | +--------+ |             |           |
|           +-------------+------------+             |           |
|           | S/SE center              |             |           |
+-----------+--------------------------+-------------+           |
| S/SW cell                                          |           |
+----------------------------------------------------+-----------+