This page is aimed to be an improved and corrected version (not a copy) of the . It is needed because there are several errors, or at least misleading bits, in them, and they often cause serious blunders. However, there may be tips contained on the official Docs that have not been ported here, so new players are advised to read the official docs anyway. This page is not self-contained: it links liberally to other pages where the matters are explained in full depth. Take it as one of several wiki indexes.