The first usage shows the ranking of the given user and all users with nearby rankings. A second argument with one or more of the letters b, s, l, w, a, u and/or h asks to show only blitz, standard, lightning, wild, atomic suicide and/or bughouse ratings respectively.
If no second argument is given, rankings for bsl are shown. For example, "rank foo bw" shows the blitz and wild ranking of the player whose handle is "foo". If 'user' is omitted, your rankings will be displayed.
The second usage shows all players ranked between the rankings of M and N. The optional third argument again limits which ratings are shown. For example, "rank 1-30 sw" lists the players with the highest 30 standard and wild ratings. "Best" lists the top 20 players in a category.
Currently, all players with at least 20 games of a particular rating type are ranked. If you ask for a player's rank and they do not yet have the 20 games needed to be an active player, the player's current rating will be displayed in the table but a line (--) will precede the handle to indicate a provisional ranking.
To omit computers from the list, use "hrank".