This will allow to set a minimum age and a maximum age requirement to be able to view a forum or threads in that forum. If the user has no date of birth set he will see an error message letting him know that he must set his date of birth in order to access those forums.
Thank you for releasing this resource free-of-charge to the Xenforo community. It's one of the most requested resources, and the only version available currently is either paid or requires adding the user to an additional group. I hope you continue to develop modifications for the community.