The patent classification system in the United States is divided into two levels: big category and small category, but there are several levels in the small category, such as the second category, the third category (with an abbreviation point before the class name) and the sixth category (with four abbreviation points before the class name). At present, there are 450 categories in the patent classification table in the United States, and the serial numbers of the categories range from 002 to 987, among which there are many vacancy numbers. There are about 6.5438+0.5 million subcategories, which is one of the more detailed classification systems in the world at present.
The U.S. patent classification number is in the form of "large classification number/small classification number". From this table alone, we can't see the relationship between classification level and upper and lower positions, but the relationship between classification level and upper and lower positions can only be understood by looking at the detailed classification table. For example, the complete meaning of classification number 2/6.3 should be 2 (major category) +455 (minor category 2) +4 10 (minor category 3) +6. 1 (minor category 4) +6.3 (minor category 5) * *.
Since 1969, the United States Patent and Trademark Office has marked the international patent classification number corresponding to the domestic patent classification in its published patent specification and bulletin.