Originally Posted by
FlyingEgghead
I'm not impressed with that "EduGuide" (granted it is from 2011). It shows an example with the comment:
This is the full paragraph from the EduGuide:
So, how many seats are actually available for sale on this flight? That’s hard to tell. In Business, this flight has 30 seats. Yet we see from the buckets (J7, D7 and I6) that the total is only 20. Remember, the number next to each booking class letter is the minimum number of seats available at this fare price. You may buy four J-fare tickets tomorrow and that fare class may still read “J7”. Also, if you add up all the numbers next to the letters, that is not the total number of seats left on the flight for sale. It may be more or less. The number can also be used as an indicator of how many seats are left for sale in that booking class.
Basically it's saying that the sum of the class values isn't representative of seats in the cabin because, for one example, 20<30. A few sentences later we do state that adding up all the numbers is not how many tickets are left for sale. However to be even clearer we will add a sentence about the classes being nested, thanks.