What I ran into yesterday, and that still confuses me, is that I have often used Unique Rectangles to solve puzzles. Generally, if you have four boxes in a square that share the same naked pair (2/6 in this case) that that is impossible. So if you have 2/6 in three of them and 2/6/N in one, that fourth one HAS to be N. But that puzzle had all four being 2 or 6 only. But I always thought that wasn't possible. So I am confused by it.