Wikians have the added user right to edit pages protected at the
wikian level. The protection level was added to prevent new users (New Wikians) from editing pages that contain Wiki guidelines or otherwise important content, like Scratch Wiki:Guidelines. Additionally, Wikians are able to edit pages in other users' userspace, though they are still required to follow the userspace policy.
Number in Group
This is an automatically assigned usergroup. Because of this, when checking permissions, MediaWiki decides on-the-fly whether users are in this group, and never actually assigns the users to the group in the database. Therefore, the number of users in this group is unknown.