These are instruction or information posts. Like info on the best way to post pictures for telling the sex of a chick, or explaining the rules of a section.
That means the thread is locked. Nobody can add another post to that thread. Either someone violated the rules of good behavior on this forum so the thread is locked to keep anyone from adding to it. Or the thread is a sticky, which means it is considered valuable for the information contained in it and the moderators don't want anyone cluttering it up with more stuff. The lock could be good or bad.
