BaseController and controller documentation mismatch

CodeIgniter's official distribution provides the BaseController class. The class name has two uppercase characters. Although
 in CodeIgniter's documentation is written (section controllers and Routing - Controllers):

!IMPORTANT

Controller class names MUST start with an uppercase letter and ONLY the first character can be uppercase.

Furthermore is mentioned that this example is not valid:

<?php namespace App\Controllers;

use CodeIgniter\Controller;

class HelloWorld extends Controller {

}

Actually BaseController has been exactly implemented as what is described to be invalid. Though it seems to be that BaseController works but not base_controller or anything similar.


Who is right?