Access Control Mechanism
Security safeguards (i.e., hardware and software features, physical controls, operating procedures, management procedures, and various combinations of these) designed to detect and deny unauthorized access and permit authorized access to an information system.
See CNSSI 4009-2015 for more information.
Implementations of formal AC policy such as AC model. Access control mechanisms can be designed to adhere to the properties of the model by machine implementation using protocols, architecture, or formal languages such as program code.
See NIST SP 800-192 under Access Control Mechanism for more information.