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Consequences for the searcher

Using the two-level system

Over the 30 years or more that the IPC was in use before the IPC reform, it had become apparent that there was a need to simplify the use of the IPC for less specialised users, but at the same time to allow large patent offices to develop the IPC further by adding more detailed subgroups.

In order to solve this problem, it was decided to define a subset of the IPC (the “core level”) as a simplified classification system that could be used as a stand-alone tool, compatible with the full IPC (called the “advanced level”).

For an international search, ie a search aimed at retrieving prior art from all major industrial countries, the advanced level should be used. The PCT minimum documentation – at the very least – are classified in accordance with the latest version of the advanced level.

For a national search, ie a search directed at retrieving documents from a specific country, the core level will usually be sufficient. Some smaller patent offices classify their documents according to the core level only, since its use requires much less specialist knowledge of the individual technical fields.

When the searcher is sure that the office in question classifies according to the advanced level, this level can of course also be used for a national search. However, when the number of documents is not very high, a core level search might still be appropriate because it will give more hits.

Documents classified in the advanced level also receive the corresponding core level classification by an automated procedure. Therefore, a search in the core level will give complete results, whereas a search in the advanced level, although more precise, will only find documents belonging to the PCT minimum collection and documents of offices using the advanced level. After performing an advanced level search, searchers should consider doing a second search in the core level, because documents of some countries are only be classified according to the core level.

On the other hand, when classifications are being used only to limit the search to a broad technical area, eg when combining classification and text search, it could be a good idea to use the core level even for searching in international document collections, because this will result in documents from all countries and be less sensitive to variations in classification philosophy.

The document content to be classified

In the past, classifiers focussed on the claims of a patent document. This was appropriate when most intellectual property offices published granted patents only. Nowadays, most offices publish patent applications before they are examined. This means that the content of the claims at the time of publication does not necessarily reflect the “real” invention or all the material that one would like to retrieve in a search.

In the rules for the reformed IPC, patent offices are recommended to classify not only the content of the claims, but also other important and possibly inventive aspects of the documents found in the description, examples or drawings. All such important features are to be classified as “invention information”. Other content in a document, which whilst being of lesser importance, may still have some search value, can be classified as “additional information”, as in the current IPC.

The distinction between “invention information” and “additional information” has only been visible on the printed document (separated by the “//” sign) up till now, but in future it will also be reflected in the databases, enabling more accurate searches.

IPC Indexing has been reduced to a minimum by converting most indexing schemes to classification. Instead of using indexing, in most cases the classifier can now simply give “additional information” classifications. The concept of linked indexing has been completely abolished, because it was never completely and consistently applied and the benefits for searching never outweighed the classification effort.