Where can USPTO personnel access USPC class definitions?
USPTO personnel can access USPC class definitions online through the Classification Home Page. According to the MPEP, All classes and subclasses (class definitions) in the USPC are available online to USPTO personnel from the Classification Home Page under the heading Search Classification Data.
The MPEP provides specific details on how to access this information: The Classification Home Page ( https://ptoweb.uspto.gov/patents/classification-resources/ ) is accessible from the desktop via the Patent Examiner’s Toolkit.
Additionally, the definitions are periodically archived: The class definitions are archived in portable document formats (PDFs) to CD-ROM every June and December.
To learn more: