The warning system works as follows.
Moderators can give a user up to 20 points a day admins can give more.
Every day 1 point will be removed.
5 points will put you on the watch list
35 points will make all your posts go through moderation
60 points will prevent you from posting
Like ip addresses only you and moderators can see how many points you have.
Moderators can place tags on posts
[mod]this is an example of a local mod tag[/mod]
[gmod]this is an example of a global mod tag[/gmod]
[admin]this is an example of a admin tag[/admin]
Admins can also lower post count and ban by username, email, ip and reverse dns.