AUTHORIZATION TO ENTER FACILITIES IS DETERMINED BY IDENTIFICATION CARD CHECKS; IT IS SAFEST TO KEEP ALL ENTRANCES CLOSED AND TO ADMIT ONLY SCREENED INDIVIDUALS. THE SIMPLEST DEVICES FOR AUTOMATIC GATE CONTROL ARE AUTOMATIC DOOR OR BARRIER OPENERS. CODED COMPUTER IDENTIFICATION CARDS ARE SUPERIOR TO GUARDS FOR CHECKING INDIVIDUALS BECAUSE OF THE REGULARITY AND OBJECTIVITY OF CARD CHECKS AND THE DIFFICULTY OF FORGING CARDS OR BORROWING CARDS FROM OTHER INDIVIDUALS. OFF-LINE SYSTEM ('STAND ALONE DEVICES') SERVING SINGLE ENTRANCE AND NOT HOOKED UP TO A CENTRAL SYSTEM ARE INEXPENSIVE, BUT LACK PROTECTION AGAINST IDENTIFICATION CARD MANIPULATION. MORE EXPENSIVE ON-LINE SYSTEMS CAN BE USED OR SEVERAL ENTRANCES AND CENTRALLY OPERATED, WITH STORAGE OF INFORMATION ABOUT ALL TRAFFIC AND THE POSSIBILITY OF LIMITING ACCESS TO PARTICULAR TIMES. TO ASSURE MAXIMUM SECURITY AND TO HINDER MALFUNCTION OR SABOTAGE, REQUIREMENTS INCLUDE IDENTIFICATION CARDS WITH A COMPUTERIZED CODE WHICH IS CHANGED FREQUENTLY, A PHOTOGRAPH OF THE INDIVIDUAL, AND OTHER IDENTIFICATION MARKINGS, AS WELL AS A STURDY IDENTIFICATION CARD READER WHICH CAN BE USED RAPIDLY AND WHICH NOTES MISTAKES IN INSERTING CARDS. PERIPHERAL DEVICES SUCH AS GATES AND BARRIERS REGULATE TRAFFIC FLOW. OTHER NECESSARY ELEMENTS INCLUDE INDICATORS WHICH SHOW WHETHER THE SYSTEM IS OPERATING SMOOTHLY, DEVICES FOR MANUAL OPERATION OF THE SYSTEM, TERMINALS WITH HARD-COPY DEVICES TO CHANGE THE PROGRAM, A CENTRAL COMPUTER, AND HEAVILY PROTECTED CABLES. THE RELIABILITY OF THE SYSTEM CAN BE IMPROVED BY USE OF REDUNDANT COOMPONENTS SUCH AS HOT-STAND-BY MECHANISMS OR REAL-TIME OPERATION SYSTEMS WITH SEVERAL PRIORITY LEVELS, AND USER PROGRAMS WHICH RECORD ALL OPERATIONS OF THE ENTRANCE MECHANISMS. MEASURES TO PREVENT UNAUTHORIZED TAMPERING WITH THE SYSTEM REDUCE POSSIBILITIES FOO MANIPULATION, AND SIGNS INDICATING THE SYSTEM'S OPERATING CONDITION AID USERS. --IN GERMAN. (KMD)