Who

Syntax: who
Syntax: who <level-range>
Syntax: who <class>
Syntax: who <class> <level-range>
Syntax: who clan
Syntax: who chat
Syntax: whogroup

WHOGROUP shows the groups currently in the game.

WHO shows the people currently in the game. Some people may choose to
remain unseen and won't appear on the WHO

WHO without any arguments shows all of the (visible) people currently playing.

With arguments, WHO can show players of certain classes or levels.
For example:

who 10 lists all players of level 10 or above
who 15 20 lists all players between level 15 and 20
who cleric lists all clerics playing
who immortal lists all immortals playing
who cleric 1 5 lists all clerics between levels 1 and 5
who clan lists all players from your clan currently on
who chat lists all players on your chat channel