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Classification search

Patent applications are classified in classification schemes on the basis of their technical content. They are assigned classification symbols, for example A43B49. This makes it easier to manage and to search for patent applications in a given technical field

Searching with classification symbols offers advantages over searching with keywords. The results of searching with keywords are less precise the further your choice of words differs from that of the applicant. Certain documents cannot be found with a keyword search, because you cannot search for keywords in documents which do not have a title or abstract. However, if these documents have a classification symbol, they can be found using that symbol.

You should bear in mind that when you search with a CPC or IPC symbol, you can only find documents to which a CPC or IPC symbol has actually been assigned. It may therefore be worthwhile carrying out certain searches twice: once using keywords and once using CPC and IPC classification symbols.

Depending on the classification level you require, you should enter the classification symbols as follows:


  • class, e.g. A63
  • subclass, e.g. A63B
  • group (main group), e.g. A63B49
  • subgroup, e.g A63B49/02
  • CPC subgroup, e.g. A63B49/028
  • CPC 2000 series subgroup, e.g. A63B2049/0282

Classification symbols are not case-sensitive. You can enter a64b49 or A63B49 or any other combination of uppercase and lowercase letters.

Do not enter blanks in classification symbols. If you encounter a symbol printed with a blank after the fourth letter or digit, e.g. A63B 2049/0235 , omit this blank, otherwise your search will not retrieve any results.

Do not use wildcards in classification symbols, e.g. do not enter A63B49* , if you want to find all child levels of this group. Entering the group alone will automatically retrieve all subgroups..

In Classification search enter the classification symbol in the search field and click Search . You can then browse the CPC scheme for more information and to find other classification symbols that might also be relevant for your search in a specific technical field.

In Smart search , you can enter the classification symbol(s) with or without the field identifier.

If you do not enter a field identifier and your search term conforms to the CPC or IPC pattern, the search engine will automatically recognise your search term as a classification symbol and use cl as the general field identifier.

To restrict your search to either the CPC or the IPC, use cpc or ipc as the field identifier.


With the launch of the Cooperative Patent Classification International (CPCI) project on 26 August 2019, Espacenet now offers the possibility of searching for documents where CPC symbols have been assigned by specific authorities. Here are some related examples of queries:


  • cpc=(C08F220/26 prox/unit=sentence EP)
  • cpc=(C08F220/38 prox/unit=sentence (US, EP))
  • cpc=(C08F220/26/low prox/unit=sentence (US, KR, EP))

Classification combination sets (C-sets, combi-sets)

In some cases patent applications are assigned more than one classification symbol. This is called a combination set ("C-set", "combi set"). These are ordered lists of linked CPC symbols created by patent examiners. Combination sets classify technical features in context or "taken in combination". The scope of a combination set can vary across technical fields. If an application has been assigned a classification combination set, this is displayed in the Bibliographic data panel under C-sets.

Classification combination sets can only be searched in Smart search with the field identifier cpcc.

You can enter up to ten classification symbols in the search field, each separated by a space, and the system will use the default Boolean operator AND. You can refine your search by combining the Boolean operators AND or OR with proximity operators.


With the launch of the CPCI project, Espacenet now also offers the possibility of searching for documents where C-sets symbols have been assigned by specific authorities. Here are some related examples of queries:


  • cpcc=(C07C37/08 prox/unit=sentence (CN, EP, US))
  • cpcc=(C08F218/08 prox/unit=sentence (C08F220/06, US, EP))