I think "none" means - just clear all check-marks and cancel all users-restrictions... It might be reprased to Check-ALL , Cancel-All
That's exactly what it means.
If you grant access to specific users, it refuses access to anybody who was not explicitly given access.
"All" grants access to all listed users, denying access to anonymous browsers. "None" removes all the explicitly granted permissions, which also removes all restrictions that go along with granting access to specific users and makes it accessible to everybody.
I created a user named "NoAccess", with a password similar to "lajkaghanerxtew". If I want to deny all access to something, I select "None", then give access to the "NoAccess" user.
