I have been reading carefully through the mediawiki documentation but I have not been able to find out how to create new groups.
When I look at Special:Userrights, I see only 3 groups : Bots, Sysops, Bureaycrats
I would like to create my own custom groups, so I can use some extensions like the http://www.mediawiki.org/wiki/Extension:Group_Based_Access_Control.
Can someone tell me how it's done, or point me to some documentation?
You can add permissions for new groups to your LocalSettings.php file and they will automatically appear in the Special:UserRights page.
For example, I wanted to disallow editing by regular users but create a "Trusted" group that was allowed to edit. The following code creates a "Trusted" group that is equal to the "user" group, except that "Trusted" users can edit but "user" users cannot.
$wgGroupPermissions['Trusted'] = $wgGroupPermissions['user'];
$wgGroupPermissions['user' ]['edit'] = false;
$wgGroupPermissions['Trusted']['edit'] = true;
$wgGroupPermissions['sysop' ]['edit'] = true;
On the Special:UserRights page, I can now check the "Trusted" box to make users trusted.