This European Standard specifies requirements for high security locks (HSL) for reliability, resistance to burglary and unauthorized opening with methods of testing. It also provides a scheme for classifying HSL in accordance with their assessed resistance to burglary and unauthorised opening. It applies to mechanical and electronic HSL. The following features may be included as optional subjects but they are not mandatory: 1) recognised code for preventing code altering and/or enabling/disabling parallel codes; 2) recognised code for disabling time set up; 3) integration of alarm components or functions; 4) remote control duties; 5) resistance to attacks with acids; 6) resistance to X-rays; 7) resistance to explosives; 8) time functions.