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Members can "tag"other members in a post. What this does is turn a username that has been tagged into a link which links directly to that users profile. An alert is also sent to the username that has been tagged informing them they've been tagged along with a link to the post they've been tagged in.
Tagging is basically a way of drawing a forum member or members to a post that you want them to see.
To tag a username in a post you simply place the @ sign in front of the username or names you wish to tag. Like this:
If the username you wish to tag contains a space you must enclose the username in brackets like this:
Some usernames with special characters cannot be tagged, or require the brackets even though they do not contain spaces. Ex: @[username!]. Usernames with brackets cannot be tagged at this time.
You can also tag a username in the topic description but that will not create a link to that username's profile. It will just send out an alert that they've been tagged.