After reading this thread, I had to look at mine.
With the instructions in this thread and looking at the diagram, it makes perfect sense.
BTW, my car is just over 3 weeks old and the top of the red float is about 1/4" below the top (which I assume is where it was when I picked it up - can't believe I need coolant already). This would seem to indicate a low level, but is it really?
Has anyone had this condition and added coolant? How much coolant did you actually add to bring it back to normal? (I realize that being only 1/4" below the top doesn't mean I would would be adding a cooresponding tiny amount.)