Todd's correct. It's two different endzones though. There's the offensive endzone (behind the QB) where it makes a safety (Denver example). In that case, the defensive team has the choice to either take the penalty or take the safety. Everyone takes the safety. On the defensive end-zone (Hawks endzone last night), if the defense causes the foul, it's 1/2 the distance and a new set of downs. No offensive player would bat it out in this case. They would fall on it for a TD (because its a fumble). Hope that clarifies the rule.