This is Moodle (http://moodle.org) autentication plugin,
that requires users to insert ID-number during login.
Without ID-number it is not possible to login.

There is also bulk action for making alot of users
not to insert ID-number. For this to work,
check /bulk_action/bulk_actions.php file at line 6.

In addition this plugin handles exceptions of users
who doesn't have an ID-number. Exceptions handling
is located in /exceptions directory.