How to manage groups on registering user.
If you want some "Regkey" to register the user into specific groups, write like this:
config.php
<?php
if( @$_POST['regkey'] == 'REGKEY_AS_YOU_LIKE' ) {
$auto_belong_groups = array( 4 ) ;
} else {
$auto_belong_groups = array( 2 ) ;
}
?>
Regkey: <input type="text" name="regkey" id="regkey" size="25" maxlength="25" value="<{$regkey|escape}>" /> - set blank if you don't know it.