Public / Private / Disabled

I was wondering how you accomplished the overriding of the Features form to allow for public / private options PER feature. Is this effectively forcing someone to be an authenticated user of role xyz when accessing a private feature or is it locking who can access that feature just to admins / a certain permission? Was hoping you could point me in the right direction before I dig through a lot of code in search of it / try to generate a solution on my own. Even pointing in the right direction would help. thanks!