Multiple Captions inside cells, 
Nav. 4.0: last one takes effect, and close td tr.
    previous captions are totally ignored.	
    If there were no caption3, caption2 would take effect.
Xena 6.0: Ignore misplaced caption tag, contents treated as text.
| cell 1-1 | cell 1-2 | 
| cell 2-1 | cell 2-2 |