Access Control List - (1) A list that indicates which users or groups have permission to access or modify a particular file on Windows NT. (2) A set of data associated with a file, directory, or other resource that defines the permissions that users and/or groups have for accessing it. In the Active Directory™ service, an ACL is a list of access control entries (ACEs) stored with the object it protects. In the Windows NT® operating system, an ACL is stored as a bi