Monitoring revisions of the IPC/CPC classification scheme

Learn how and where to monitor classification revisions.

Keep up to date with classification revisions to ensure your search settings continue to deliver optimal search results for the areas you are monitoring.

This article explores why it is important to follow updates to the International Patent Classification (IPC) and the Cooperative Patent Classification (CPC) schemes and how these changes directly impact the effectiveness of your prior-art search.

Although the IPC and the CPC share the same structure, they are standalone classification systems. The IPC is the more widely used standard, while the CPC is an extension of the IPC offering a more detailed classification.

Both the IPC and the CPC are structured hierarchically into sections, classes, subclasses, groups and subgroups, enabling patents to be categorised into specific technological domains. The classification becomes more detailed with every further subdivision:






Human necessities



Baking; edible doughs



Machines or equipment for processing doughs



Mixing or kneading machine for the preparation of dough



With horizontally-mounted mixing or kneading tools

As technologies advance and new fields of innovation emerge, the classification schemes are continuously revised and updated to adapt to new technological developments. This process involves reclassifying several documents. It is therefore important to regularly check these revisions and adjust any search queries you may have saved accordingly. If you do not monitor these revisions, you run the risk of overlooking crucial prior-art references, which can result in an incomplete prior-art search or search results with too much "noise".

To avoid missing relevant updates, we advise users to consult the following information and documentation regularly for both manual (individual) and automated searches.

  • Notice of Changes area of the official Cooperative Patent Classification website.
    CPC pre-release information such as scheme files, notices of changes, concordances, etc. are posted on the CPC website. Revisions are published there approximately one month prior to the official entry into force of the changes.

    Fig. 1. Tab to access CPC Revisions on the Cooperative Patent Classification website.
Tab to access CPC Revisions on the Cooperative Patent Classification website.


  • Classification search
    This tool is integrated into the Espacenet interface.
    Here you can activate the highlight function in the classification scheme to identify CPC revisions and toggle the differences between the CPC and the IPC. You can also directly access the CPC website and activate scheme notes and warnings about the changes.
    For more detailed information on how to use this tool, go to the Help section for Classification search.

    Fig. 2. Buttons for customising the classification index and displaying changes and updates in a classification search.
Displaying the buttons for toggling “notes and warnings” and “dates of updates”


  • International Patent Classification (WIPO)

This webpage contains all relevant information relating to the IPC and forthcoming revisions (the next revision is currently planned for 1 January 2024)

With the above links and information, you should have all you need to understand and monitor the schemes and revisions. However, our users have some specific questions that go beyond the basics of the schemes, for example on the recent CPC revision involving a move from the subclass H01L to a new class H10. For this we take you on a deeper dive into this subject, using the following questions we received from users and our answers to them:

Q: What happens to the H01L CPC subclasses that do not yet correlate to the new H10 class?

A: Generally, the older H01L group will remain in the CPC scheme until the CPC reclassification has been completed. In Classification search, you can activate warnings to have ongoing reclassifications indicated. Only after completion is the subclass removed.

Q: Is it possible to search for the H01L CPC subclass in applications where reclassification has been completed?

A: No. Subclasses where all documents have been reclassified, i.e. where there are no warnings anymore, can only be searched using the new classification symbols. This is the main reason why it is important to keep your search settings up to date.

Q: Does the Classification search tool in Espacenet still display the abolished CPC symbols and their definitions?

A: No, it doesn’t. Once the reclassification has been completed you will no longer be able to retrieve this information in the classification scheme. However, via the CPC website, you can still access abolished CPC symbols and their definitions in the "Searchable NoC Archive" (hosted on the USPTO website, see direct link below), where you can also find a link to the list of deleted CPC symbols.

Visit the EPO discussion forum to find the answers to your questions and exchange views and expertise with patent professionals.


Keywords: Classification, Cooperative Patent Classification, CPC revisions, Notice of changes