On the topic of guidelines, the purpose of the up- and down-vote arrows is not well-defined. Are we supposed to use them as "like" and "dislike", "agree" and "disagree", or "adds-to-discussion" and "doesn't-add-to-discussion"? Even "flag"- is that for spam, for rude posts, or for offtopic posts?

I've seen these things discussed, and pg has given his opinion on some of them in comment threads, but we should decide and put the answer in the site guidelines.