===== Sandbox =====
^ ^col 1 ^  col 2  ^  col 3&4^^
^row a  |:2 a1-b1  |  :3_ a2-c3|| a4 |
^row b&c :2- | b4|
^c1  ^ c4|
^row d  |d1  |  d2  |  d3| d4 |

^   ^ col 1 ^ col 2 ^ col 3 | col 4 ^
^ row 1 | 1 | 2 | 3 |
^ row 2 | col span || end |
^ row 3 | 1 | 2 | 3 |