Electrical Patents Index Manual Coding system - Structure

The Electrical Patents Index Manual Codes (EPI manual codes) system is a hierarchical classification and indexing system, intended for use as an online retrieval tool for abstracts of Electrical and Electronic engineering patents. The system was originally based, in part, on the International Patent Classification (IPC) and currently includes approximately 9,000 codes.

Since their introduction in 1980, the EPI Manual Codes have been revised four times (in consultation with customers) to accommodate changes in technology, provide finer subject matter breakdown and thus improve information retrieval.

Format Of Manual Codes

EPI coverage is arranged in six sections (S-X). Within each section, EPI classes (50 in total) provide a more detailed breakdown of subject material. At further levels of the hierarchy, the manual codes are structured so that an increase in the number of characters comprising the code corresponds to further levels in the breakdown of the subject matter associated with each class.

Patent Selection And Classification

Patent documents are selected for classification and indexing using the EPI Manual Codes in one of two ways: a) due to the IPC assigned by the patent office or b) manual selection, based on the electrical content of the invention, of those patents not assigned a ‘guaranteed IPC’.

Patents are manually selected; a) based on their relevance to the electrical/electronics industry, which includes inventions which may or may not be intrinsically ‘electrical’ in themselves, e.g. insulating tape, or b) having significant electrical content e.g. a novel RF amplifier circuit.

EPI Manual Codes are intellectually assigned by Derwents’ indexers, and as such, no direct concordance between EPI Manual Codes and IPCs is guaranteed. Also, codes other than those corresponding to the IPC may be assigned as appropriate according to the technical content of the patent.

This approach to the selection and classification of individual patents based on their content is an obvious improvement over selecting records based upon IPC only.

Assignment Of EPI Manual Codes

EPI Manual Codes are assigned in order to highlight the novel technical aspects of an invention, and are therefore normally assigned according to the details of the novelty described in claims. In addition, codes are applied to indicate the applications of an invention, depending upon either the electrical content of the invention or its intended use. The information used to index the application aspects of the invention are often taken from the main body of the patent specification.

Therefore, the EPI Manual Codes cover both the novel technical details disclosed within the patent, and the invention’s application. For example: a patent for a novel arrangement for reducing harmonics and ripple in a power supply circuit designed for use in a computer would be assigned the appropriate code from Derwent class T01 (Digital Computers) - T01-L01 (Power supplies, stand-by arrangements), and a code from section U24 (Amplifiers and low power supplies) - U24-D01E (Reducing harmonics and ripple).

This approach enables users having different requirements to retrieve documents of specific interest to them. A user interested in harmonics and ripple in power supplies per se. would be able to retrieve records using the U24 code, while a user specifically interested in patents about power supplies in computers would also be able to retrieve relevant records using the T01 code.

Manual codes are frequently used in combination to represent a particular topic. Some subjects may routinely be assigned two or three manual codes.

Documents Assigned Manual Codes

EPI codes have been assigned to patent records since the beginning of the EPI service (Derwent Week 8018). Manual Codes are currently assigned to all Basic patents in EPI and CPI. Prior to Derwent week 199510, title-only records (i.e. those records without an abstract) had EPI classes assigned, with the exception of Chinese and Japanese patents, which received full EPI manual coding.

Additional Search Terms

As part of each Manual Code entry, additional search terms are given for most code definitions. These comprise individual terms or groups of terms which might assist users in devising search strategies. The terms have been derived intellectually by Derwent coders, aided by online searches, to determine the most frequently-occurring terms in titles of records to which the code has been assigned.

In order to further enhance retrieval, terms of interest within the code title definition itself, and in the accompanying scope notes, could also be used. In addition, terms appearing against higher level codes in the hierarchy may be employed.