(Present only when the in-built AuthUser username/password functionality is used). An array of different authentication mechanisms to be used for user authentication. Array keys are a tag for the mechanism; values are a function callback that will be called with the properties $pagename, $id, $password, and $pwlist. Oh... could someone else make this make sense, please?!
A switch to control whether or not changing a page's attributes causes any existing passwords to be forgotten. The default is that changing attributes forgets any passwords entered; this can be changed by setting $EnablePostAttrClearSession to zero.
Control whether passwords are saved as part of the session. If set to zero, then session passwords are never saved (although any AuthUser authentications are still remembered).
This sets the required authentication Level that is necessary to perform an action. When using the following example in your config.php you need to be authenticated as editor in order to view the page history: