My comment about a P trap was because he referenced a floor drain which by definition has a P trap. The question about the height the the flange is on a par with “My drain is stopped up. What should I do?”. If they do not know the answer to a question as simple as that, and it is really intuitive, then they should take the pieces and figure it out. Besides, there have been hundreds of replies stating that the flange sits on top of the finished floor that he could have located with a little research and effort. When you give an answer, you are giving him a fish. If you tell him where to find an answer, but try to prevent him from making a serious mistake in the process, you are teaching him to fish.