Basically, when a user gets banned it could say "Banned" instead of registered user, and tale away all privileges. Only the Mods can give this status. And no chat entry.
Also, don't let a banned user edit his/her profile.
Just a suggestion.
There already is a banned user type - when a user gets banned they already lose all their privileges and cannot post on chat.
For me it actually does say "(blocked)" right after "Registered user". But maybe that could be made available for everyone, I'll check.
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