108041401000000000 steel fasteners include screws, bolts, nuts, steel washers, rivets, cotter pins, pins and taper pins, circlips and other steel fasteners. If the code of 100 and the code of 10 can represent the parts to be described completely and unambiguously, the code of 10 will be more popular. OPITZ code consists of 9 digits, the length of KK-3 code in Japan is 2 1 digit, and the length of MICLASS code in the Netherlands can reach 30 digits. The former German Democratic Republic and Germany established a classification coding system consisting of 72 digits, which was implemented as law. It must be noted that no matter how complicated and detailed the classification and coding systems are, they can't describe all the information of parts in detail, because the classification and coding systems generally only describe the information of parts in a macro way without excessively pursuing all the details of the information of parts.