Originally Posted by mbluecpa

This is from the pda site:

What are blocked seats?

On occasion Continental will withdraw or “block” some seats from being sold. There are a few explanations for why this could happen. For example, when Economy Class on a flight is booked over capacity and the premium cabin (i.e. First Class or BusinessFirst) is not, we'll sometimes withdraw some premium cabin inventory from sale to reduce the chances of an oversale. Another common example is on our long-haul flights. Specifically, on Continental flights that are scheduled to be twelve hours or more, up to four BusinessFirst seats may be blocked for crew rest. These blocked seats may not be sold or occupied for any purpose other than crew rest. The least common example is when a seat is broken and can’t be repaired before the flight departs. In these cases, the seat will be blocked from inventory until it is repaired.