An Access Control List (ACL) can represent any set of physical or virtual objects that you wish. For the purposes of demonstration, however, we will create a basic Content Management System (CMS) ACL that maintains several tiers of groups over a wide variety of areas. To create a new ACL object, we instantiate the ACL with no parameters:
$acl = new Zend_Acl();
Until a developer specifies an "allow" rule,
access to every privilege upon every resource by every role.