IPC - International Patent Classification System

The IPC system operates from about 1973 and is used by all the major patent offices when classifying documents. Because IPC heading s are assigned by a variety of different bodies, patent family members are often classified amongst a number of different IPC headings.
The IPC is reviewed every 5 years but existing material is not retrospectively re-classified. As a result, when conducting searches it is often necessary to classify a search subject more than once in order to select the appropriate classifications for the entire search period.
For a comprehensive manual search, RWS searchers will utilise the IPC, probably in combination with other classification systems to produce search lists. The best and some marginal headings would be covered to allow for differences in classification of documents by various Patent Offices.

CAPRI

For searches extending before 1973 (e.g. a validity search of a mechanical invention), RWS utilises the CAPRI system containing some 12,000,000 reclassified documents from major countries. CAPRI stands for the Computerised Administration of Patent documents Reclassified by International Patent Classification, which in simple terms means that all patent documents which were published before 1973, i.e. before the effective starting date of the IPC, have been retrospectively reclassified by patent examiners, according to the IPC. For example, using the CAPRI system, patents indexed under a particular IPC heading, say F16D 47/06, can be reviewed for the period 1920-1972, while the period 1973 to date can be covered according to the same IPC heading. This is particularly significant for general and mechanical inventions; it allows a subject matter search to be conducted over a long search period and on a consistent technical classification basis.

ECLA - European Patent Office Classification System

European Patent Office (EPO) examiners instigated the ECLA system originally as an internal search tool. ECLA headings are assigned to patents by EPO examiners on the basis of subject matter; they do not depend upon the IPC printed on the original document. In general the ECLA provides a number of sub-divisions for IPC headings and is often considered as a prototype for the next edition of the IPC. As the ECLA is far more sub-divided than the IPC, it is possible to select definitions which are more narrowly defined (i.e. the search is more closely targeted to the subject area). However, under the ECLA system less cross-referencing between headings occurs than under the IPC system and therefore an ECLA search is not as broad as the corresponding IPC search.

An advantage of searches by ECLA is that when new headings are created material in existing headings is retrospectively re-classified (as is the case in the new US Patent Classification for example), and therefore the search can be conducted using one or several headings that cover the entire search period. In addition the ECLA is updated monthly to cope with changes in "fast moving" technologies.

The ECLA headings never appear on the printed publication, even on EP applications or patents. RWS stores ECLA codes within its own proprietary database.

USPC - US Patent Office Classification System

Whereas the IPC and ECLA are based on the same principles, the US classification system is organised very differently. Many Intellectual Property professionals in Europe are unfamiliar with the classification system. Likewise, US examiners are not very accurate in assigning IPC headings to patents and mainly work from a rather crude concordance list. As a result, to search US publications by IPC either manually or electronically is prone to deliver highly unreliable results.

RWS never conducts searches or watches of US publications by the IPC accorded by US examiners. We are well-versed with the USPC. An advantage of USPC searches is that all US publications are retrospectively re-classified when new headings are created (as in the case in the ECLA) and therefore the search can be conducted using one or several headings that cover the entire search period.

Alternatively, we may also search US patents via the ECLA system (see above). The classification headings are in this case much more reliable than the IPC headings given to US patent documents because they have been accorded by EPO examiners who are experts in this system.