AN EXCELLENT QUALITY LOCK CYLINDER FOR HIGH SECURITY WILL RESIST PICKING OR FORCING, BE MADE OF HARD AND SUITABLE MATERIALS, AND CONTAIN HARDENED STEEL ANTIDRILL PINS AT VULNERABLE POINTS. THE NUMBER OF KEYS FITTING THE CYLINDER SHOULD BE KEPT AS LOW AS POSSIBLE, BUT THE NUMBER OF KEYS THAT CAN OPERATE MORE THAN ONE CYLINDER IS DETERMINED BY THE VARIETY OF POSSIBLE BITTING CODES IN A SYSTEM. THE BITTING CODE FOR A KEY IS CUT; THE LARGER THE NUMBER OF PINS, THE GREATER THE VARIETY OF THE BITTING CODES POSSIBLE IN A LOCK CYLINDER ARE IMPRACTICAL OR ABLE TO BE OPERATED BY SEVERAL DIFFERENT KEYS. FOR HIGH SECURITY SITUATIONS, THEREFORE, CYLINDERS OFFERING 23 MILLION OR MORE NONINTERCHANGEABLE BITTING CODES ARE RECOMMENDED. THE MANUFACTURER OF A HIGH-SECURITY CYLINDER OFFERING MANY BITTING CODES ASSIGNS A PERSONAL BITTING CODE TO EACH CUSTOMER AND THEN REMOVES THE ASSIGNED CODE FROM HIS CODE BOOK FOR CERTAIN TYPES OF KEYS. WHEN SELECTING RESTRICTED KEYS, THE CUSTOMER SHOULD CONSIDER THE MECHANICS AND TIME INVOLVED IN ACQUIRING EXTRA KEYS, SINCE SOME TYPES OF RESTRICTED KEYS CAN BE DUPLICATED ONLY AT THE FACTORY, OR NOT AT ALL. AFTER SELECTING THE PROPER LOCK AND KEY SYSTEM, THE SECURITY MANAGER SHOULD SELECT AN OVERALL KEY CONTROL PLAN BASED ON BUDGET LIMITATIONS AND SECURITY LEVEL, SELECT A KEY THAT CANNOT BE DUPLICATED BY ORDINARY MEANS, AND ENSURE PERSONNEL AND MANAGEMENT SUPPORT. IMPLEMENTING A KEY CONTROL PROGRAM INVOLVES STUDYING THE AREA IN WHICH IT WILL BE ESTABLISHED, RECORDING WHO IS TO GET KEYS, AND ESTABLISHING PROPER KEY STORAGE. ACQUIRING ADDITIONAL KEYS AND CYLINDERS AND WHEN TO CHANGE LOCKS ARE ALSO DISCUSSED. ILLUSTRATIONS ARE INCLUDED. (PAP)