US Patent Classification System (USCS)
Some Aspects of the USCS
- Currently contains 464 Classes including Utility, Plant and Design Classes
- Patent classification is based on: Disclosure encompassed by allowed claims with the original placed in the subject matter covered by the most comprehensive claim, regardless of dependency [However, relatively few patent examiners are aware of or follow this basis], see Chapter 900 of the MPEP (Manual of Patent Examining Procedures)
- Combinations and more complex subject matter is placed nearer the beginning of a class schedule; subcombinations, elements and broader and more general subject matter are placed nearer the end of class schedules
- "Residual Classes" take subject matter not explicitly classified elsewhere, e.g., 29 and 156
- Class definitions provide additional information and clarifications, e.g., possible analagous and related classes, restrictions, lines between classes
- Refer to the TAF Program reports (uspto.gov) to learn about technology trends, such as classes containing the most issued patents yearly since 1985 [this helps to identify "crowded art areas", i.e., areas containing high concentrations of recently issued patents that are difficult to distinguish]
- Designation of classes and subclasses relative to three broad areas, i.e., chemical, electrical and mechanical, are roughly in accordance with the Examining Sectors [assignment of subject matter areas, i.e., classes/subclasses for each art unit, are given at uspto.gov [when the desired classification is known, the particular art unit and examiners can then be determined]