Though, it's sort of fucked up. Clan tags have to be unique and are taken from the "Abbreviation" setting of a steam group. Anyone in that steam group can use that Abbreviation as their clan tag. It seems to disregard special characters (ie; {us} is the same as us). One thought is, we could have a private group of people who have admin, so you would be able to don a ibis.a clan tag. instead of changing your profile name all the time.

You can access the clan tag system via Options --> Multiplayer --> advanced, then clicking the clan dropdown.