How I Wrapped my Mind Around The Japanese F-Term

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When I first started learning about patent searches after coming to Landon IP, one of the most difficult concepts for me to grasp was the Japanese F-term classification system. I was used to hierarchical classification systems, so I didn’t have much trouble with the Japanese File Index (which expands on the IPC). I was thrown for a loop, though, when I first saw the F-term lists at the Industrial Property Digital Library. These weren’t standard lists; these were tables with  dozens of rows and  columns.  One F-term theme code (e.g. 4D006) can have multiple terms codes (e.g. GA, HA, JA, etc), and each term code can have multiple dependent term codes (e.g. GA00, GA01, GA02, etc.). Add the extension codes at the end, which “apply to each and every viewpoint under that theme code,” and you have a very confusing classification system. According to the Intellogist glossary page on F-terms and the F-Index, “there are around 1,800 theme codes, and 350,000 terms codes contained within the F-term classification system.” How can this extremely specific classification system, which looks at a theme from every possible viewpoint, be used? Do you apply a single, very specific F-term to a patent, or do you apply a broad theme code and all dependent term codes to it? I couldn’t escape from the hierarchical classification mindset.

I tried reading everything I could in order to understand the F-term. I read the glossary page on Intellogist and Kristin Whitman’s insightful blog post on F-terms. Still, nothing worked. Finally, I asked Chris Jagalla if he could try explaining the concept to me.  He gave me a brilliant comparison that finally helped me understand  F-terms. Read on to learn about my path from confusion to enlightenment!

Finding the F-terms in the IPDL

Before I give away the ending, let’s start at the beginning: the IPDL. The IPDL is a free search system provided by the JPO that allows users to search for Japanese patents. Users can also search for the definitions of both File Index (FI) classifications and F-terms.

Japanese Patent Office (JPO) Industrial Property Digital Library (IPDL)

If you want to find a corresponding F-term for a Japanese Patent, first conduct a basic text search through the PAJ to find some similar patents to the technology or process you are looking for. In my test search, I searched for the concepts of “hair” and “clip” to see if I could find any patents for hair clips.

The PAJ- Text search at the IPDL

I found some relevant results in my search and I noticed that these patents have a common classification code of A45D 8/00. I then went to the Patent Guidance Map within the IPDL, so I could find the corresponding F-term for this FI classification. I searched within the FI field, since the results give both the definition of the classification code and the corresponding F-term theme code. I found that the definition for A45D 8/00 is “Hair-holding devices; Accessories therefor,” and the corresponding F-term is 3B039. I then searched for 3B039 in the F-term field.

Patent Guidance Map- Searching for File Index and F-terms

Below is the F-term list for the theme code 3B039. In this case, the theme code has no term codes. The definition for the theme code is above a list of the corresponding FI codes. Simple enough, right?

F-term list for 3B039

Wrong. Below is the F-term list for theme code 4D069. The image below is only a small section of the table of dependent term codes for 4D069. This example theme code is also shown on the Intellogist glossary page for the F-term and File Index.

F-term list for 4D006

Understanding the F-term

So how did Chris explain the concept behind these complex tables of codes? How did I finally escape from my hierarchical rut? Chris compared the process of assigning F-terms to a common blog feature: tagging. Many F-terms are assigned to a single document, just as multiple tags are assigned to a single blog post to specifically identify the multiple themes of the post. Kristin elaborates on the use of multiple F-terms per document in her blog post “Are you effectively using Japanese File Index and F-terms?” Kristin says that “in a 2008 article on the subject, Stephen Adams stated that Paterra had calculated an average of 14 F-terms per document, and that  some individual documents were known to bear more than 50 terms.”

These multiple F-terms provide a richer view of the different processes, industries, technologies, materials, etc. which go into the creation and use of the patent. Multiple classification codes from a hierarchical classification system may also be applied to a patent, but the F-terms offer a unique level of specificity and variety of viewpoints on a single theme, which the hierarchical classifications lack.

So I had an “ah-ha” moment through a blogging analogy. Have you ever experienced an epiphany about patent searching concepts? Please share them in the comments!

Patent Searches from Landon IP

This post was contributed by Joelle Mornini. The Intellogist blog is provided for free by Intellogist’s parent company Landon IP, a major provider of patent searches, trademark searches, technical translations, and information retrieval services.


2 Responses

  1. Joelle,
    I share your view that understanding the Japanese F-Term system with its theme-codes and matrix of viewpoints is quite challenging. But if Japanese patents are important in the field you are working in, it is difficult to do a good prior-art search without considering the F-terms for search. Especially when the alternative is to base your search on the abstract… So it is well worth to take the effort and try to understand the system behind it.
    While you did a great job in explaining and finding a good analogy, maybe you’d like to add the following e-learning module that I found on the EPO website – originating from their interesting “Search Matters” seminar. This 90 minute presentation from 2007 – called “Searching Japanese databases with classification terms” can be found by going to and entering “Japan” as search term. Alternatively select “Open-access modules” – “Events” – “Search Matters 2007”. Or here -for your convenience – the direct URL that is shown when starting the module: . Within the 90 minutes various aspects of the classification search are shown – including some practical examples.

    I think it this e-learning module can be quite helpful in better understanding the F-Term system. Especially as you can follow the talk in parallel to the presentation and can stop / restart at your convenience – so a (necessary) coffee/tea-break will be no obstacle ;-)

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