No End Gap Penalty.
We saw this thing before, and it means the same thing as before, but now there is no penalty for end gaps (leading or trailing). Hence many optimal alignments will be different than those we would have obtained on page 3 using the same sequences (as we saw on the previous page). Play around with this. Sometimes you may get weird results. For example, if you align "AAGA" with "AAA", you'll get one optimal alignment when penalizing end gaps, and a very different one if not. Give it a try. By the way, what's the minimum optimal score for an alignment that does not penalize end gaps?

On the next page we'll look at fully local alignments.