LISTED IN ORDER OF THEIR DEGREE OF RESISTANCE TO FORCE, DOOR TYPES INCLUDE WOOD OR SYNTHETICS WITH CARDBOARD PANELS; METAL, WOOD, OR SYNTHETIC-FRAMED DOORS FILLED WITH WOOD OR A SIMILAR MATERIAL; SOLID WOOD DOORS AT LEAST 40 MM THICK; AND METAL DOORS. GLASS INSETS REDUCE THE SAFETY OF ANY OF THESE DOORS. LOCK TYPES DESCRIBED ARE TUMBLER LOCKS WITH VARIOUS TUMBLER SYSTEMS AND KEY TYPES; A TWO-PART LOCK SYSTEM WITH A LATCH TO HOLD THE DOOR CLOSED AND A LOCKING SYSTEM; OVAL, ROUND, OR PROFILE CYLINDER LOCKS FREQUENTLY MOUNTED ONE THE DOOR AS SECOND LOCKS; DEAD-BOLT LOCKS; AND CENTRAL LOCKING SYSTEMS. FOR EACH LOCK, THE SIZE, THE TYPE OF MOUNTING, THE NUMBER AND ARRANGEMENT OF KEY WARDS, THE NUMBER OF TUMBLERS AND OTHER FEATURES ARE DEFINED TO ASSURE MAXIMUM SECURITY. LARGE DECORATIVE DOOR FITTINGS AND NAME PLATES OF STEEL OR OTHER METALS ARE AN EFFECTIVE MEANS OF STRENGTHENING A DOOR, BUT SHOULD BE MOUNTED WITH MEANS OTHER THAN WOOD SCREWS AND REINFORCED TO PREVENT REMOVAL OF HARDWARE AND LOCKS. FIGURES ILLUSTRATE VERY SPECIFICALLY THE FUNTIONING OF VARIOUS LOCKS AS WELL AS TYPES OF KEYS AND SECURITY FITTINGS. --IN GERMAN. (KMD)