Right. As I understand it, the classes below Y are all a subset of the Y fare class. So this example shows that there are at least 7 coach seats available, of which they are willing to sell all of them at full Y, but only 5 at B, and only one of those seats at H or M. Revenue management is a very complex department, from what I've seen, it's really an art to "squeeze" the most revenue they can out of each seat.

dan