Comparison Between IPC and USPC

By: Hsin-Hsin Liu

I. Purpose of the paper
Patent search can be accomplished by many ways such as keyword search. Locating the proper patent documents may not be easy. With classification systems and the various search tools that were developed in relation to those systems, it is not as complicated as it might seem on the surface. Designing a classification system was started over 100 years ago to prevent drowning in the flood of patent literature. The growth of the files of patent specifications led the patent offices to develop classifications of their own. In this paper, I would compare International Patent Classifications (IPC) and U.S. Patent Classifications (USPC). The differences between these two classifications in focus, scope and result are review here as well.

II. Overview of Patent Classification
The primary purpose of classification systems is to facilitate the searching and retrieving of patent documents by patent offices and users. The offices which have to handle the very large number of patent applications they receive and the patent documents published each year are faced with the problem of the maintenance of the search files containing the published patent documents.

Classification systems are hierarchical in nature with main headings covering a general area of technology and sub-headings covering a given type of invention. Each sub-heading has a specific number, which is assigned to all the patent documents relevant to that category. The systems allow people to identify the classification areas in which the subject technology can be. After having identified potential classification areas from the index, the class schedules must be consulted to determine the best and most exact classification groups in which to search. Various classification systems exist and most have been designed so that each technical aspects of an invention to which a patent document relates can be classified as a whole. Effective classification of patent documents is essential for searching the growing number of patent documents. IPC and USPC are the major patent classification systems.

III. International Patent Classification

BACKGROUND
In order to assess the universal novelty of the "invention", it becomes necessary to include in the patent documents published by domestic office as well as foreign countries. Thus, the need for an international classification system to solve the problems becomes more and more apparent. The Strasbourg Agreement concerning the International Patent Classification, concluded in 1971 aimed to overcome the difficulties caused by using diverse national patent classification systems. The common classification system defined by the Agreement is applicable to patent and utility model documents.

IPC is published and managed by the World Intellectual Property Organization (WIPO). Versions are revised and amended every 5 years by an international committee of experts in order to make the system perfect and to follow the technical progress. Patent offices use the current version for assigning IPC codes and do not re-index their documents when a new revised edition is published. The current (seventh) edition has entered into force on January 1, 2000. The IPC exists in two authentic versions, English and French, which are published as printed publications. A consolidated version including all editions is available for a fee on CD-ROM and in many languages. The authentic versions (English and French) of the sixth and seventh editions of the IPC are made available on the WIPO Web site, permitting the user to browse the text of the Classification in order to find the relevant IPC symbols.

BASIC PHILOSOPHY
While elaborating an IPC system, there was a question of whether the IPC system should be based on the function-oriented principle or an application-oriented system. Function-oriented principle means a system is according to the intrinsic nature or function of a process, product or apparatus, independent of its field of application. It places embrace a wider concept. The application-oriented system, on the other hand, is according to the particular use or application of a process, product or apparatus. This tendency towards preservation of the complete character of an invention rather than its dissolution into component aspects is further reflected in the facts that the IPC employs the principle of classifying inventions according to their intrinsic nature. However, it was finally agreed that a system combining both principles would best meet the needs of all users. Consequently, IPC is a combined function/application classification system in which the function theoretically takes precedence. In the IPC, except when its application alone determines its technical characteristics, an invention is classified according to its "function," which means how it operates.

STRUCTURE OF IPC
The Strasbourg Agreement establishes the International Patent Classification which divides technology into eight sections with approximately 69,000 subdivisions in its seventh edition. Each subdivision has a symbol consisting of Arabic numerals and letters of the Latin alphabet. The IPC is a hierarchical system comprising:

Sections: (G)
Classes: (G 09)
Subclasses: (G 09 G)
Main group: (G 09 G 1/00)
Subgroup: (G 09 G 1/23)

1. Sections

The IPC attempts to cover all technological field in which inventions susceptible to patent protection may be made. Each section is designated by one of the capital letters A through H. The section title is to be considered as a very broad indication of the contents of the section. The IPC divides into eight sections.

A. Human necessities
B. Performing Operations; transporting
C. Chemistry; metallurgy
D. Textiles; paper
E. Fixed construction
F. Mechanical engineering; Lighting; Heating; Weapons; Blasting
G. Physics
H. Electricity

Each section is followed by a summary of the titles of its main subdivisions.

Section A HUMAN NECESSITIES
Subsections
Agriculture
Foodstuffs; Tobacco
Personal or Domestic Articles
Health; Amusement

2. Classes

Each section is subdivided into classes and the symbol for each class is two-digit number following the section symbol. There is class title to indicate the content of the class.

Subsection: Foodstuffs; Tobacco

Class A 2l BAKING; EDIBLE DOUGHS
Class A 22 BUTCHERING; MEAT TREATMENT; PROCESSING POULTRY OR FISH Class A 23 FOODS OR FOODSTUFFS; THEIR TREATMENT, NOT COVERED BY OTHER CLASSES
Class A 24 TOBACCO; CIGARS; CIGARETTES; SMOKERS' REQUISITES

3. Subclasses

Each class comprises one or more subclasses.
A 47 FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS;SUCTION CLEANERS IN GENERAL
A 47 B Tables; Desks; Office furniture; Cabinets; Drawers; General details of furniture
A 47 C Chairs; Sofas; Beds

4. Groups
Each subclass is broken down into subdivisions referred to as "groups," which are either main groups or subgroups.
Each main group symbol consists of the subclass symbol followed by a one- to three-digit number, the oblique stroke and the number`00. The main group title defines a field of subject matter considered to be useful in searching for inventions. Example: A 01 B 1/00 Hand tools
Subgroups form subdivisions under the main groups. Each subgroup symbol consists of the subclass symbol followed by the one- to three-digit number of its main group, the oblique stroke and a number of at least two digits other than 00. The subgroup title defines a field of subject matter within the scope of its main group considered to be useful in searching for inventions. The title is preceded by one or more dots indicating the hierarchical position of that subgroup. The subgroup title is often a complete expression, in which case it begins with a capital letter. A subgroup title begins with a lower case letter if it reads as a continuation of the title of the next higher group. In all cases, the subgroup must be read as being dependent upon, and restricted by, the title of the group under which it is indented.
Examples: A 01 B 1/00 Hand tools
1/24 . for treating meadows or lawns

CLASSIFYING RULES

In a number of places of the Classification, some particular classifying rules are specified to limit multiple classification, to improve consistency and to facilitate searching without harming its quality. The places where such rules apply are clearly marked by a note at the highest place covered by such classifying rules. Such rules are:

(a) Last Place Rule - a "last place rule" has been introduced when a particular technical subject is covered by two or more places of the same hierarchical level or indentation. A technical subject is only classified in the one of these places according to this rule. In each part of the Classification (class, subclass or group), where this rule applies, this rule is clearly set out in a note specific to the subject matter concerned. For example, see the relevant notes in A 61 K, C 07, C 08 G, C 10 M, G`07 D 5/00.
(b) Other Rules - In a limited number of places in the Classification other particular rules exist which are clearly specified in notes at the places concerned, e.g., B`32`B, C`04`B`38/00, C`08`L, G`05`D.
ARRANGEMENT AND LAYOUT ON PRINTED DOCUMENTS

The following examples illustrate the presentation of classification symbols and indexing codes on a document :
C08 F 210/16, 255/04

// A 61 K 47/00, C 09 J 151/06 (C 08 F 210/16, 214:06)
(C 08 F 255/04, 214:06)

These symbols and codes indicate:

two classification symbols representing invention information,
C`08 F 210/16 and C 08 F 255/04;
two classification symbols representing additional information,
A 61 K 47/00 and C 09 J 151/06;
two sets of linked indexing codes, (C 08 F 210/16, 214:06) and (C 08 F 255/04, 214:06), which indicate, respectively, that the ethene- propene copolymer, besides the already indicated monomers, contains vinyl chloride, and that vinyl chloride has been polymerized on to an ethene- propene copolymer.

IV. U.S. Patent Classification

A national classification system providing for the storage and retrieval of patent documents is managed by the U.S. Patent & Trademark Office (USPTO). A fundamental principle of the USPC System is that each class is created by first analyzing the claimed disclosures of the U.S. patents and then creating various divisions and subdivisions on the basis of that analysis. All similar subject matter is gathered together in large groupings to create classes. These classes are then subdivided into smaller searchable units called subclasses.

The system comprises three main categories, chemicals, electricals and mechanicals, and the three groups from about 400 classes which are themselves subdivided into more than 125,000 individual subclasses. There are continual changes in the classification system. New classes and subclasses are established due to new developments in science and technology, and old classes and subclasses are abolished when rendered obsolete by technological advances. Additionally, changes to classes and subclasses may result from an effort to streamline and update the definitions. The USPC is updated several times every year and all individual patent document classifications correspond to the most recent revision. The USPC can be consulted free of charge on the Internet.

Philosophy

A variety of rationales have been developed over the years to subdivide the USPTO's classified files into searchable units. Collection of art is based on each of the following rationales.

Industry of Use	The industry employing the art or the use to which a device is put.
Proximate Function	Similar processes or structures that achieve similar results by applying similar natural laws to similar substances are considered to have the same fundamental utility and are grouped together.
Effect or Product	The results produced by the art.
Structure	The structural configuration or physical makeup of the object. (such as chemical compounds)
Ornamental Appearance	Separate collection of Design classes. Classified based on function or intended use and subdivided by ornamental, appearance and structure.

Classification Schedules

The sequence or pattern arrangement of the subclasses within each class is called the class schedule. The order in which a subclass appears in the schedule establishes the order of superiority between the concepts provided for. The location of the subclass within a schedule hierarchy is paramount. Subject matter will be found in the first appearing coordinate subclass or its indents that will accept that subject matter.
Subclass titles that do not have a dot between the title and numeric designator for the subclass are referred to as "Main Line" subclasses. The number of indent levels refers to indented subclasses. Subclasses positioned at the same level of indentation are referred to as "coordinate" subclass, provided that a subclass with a lesser indent level is not located between the subclasses being compared.
Assigning Classifications to Patent

The bulk of patent documents stored in the USPC system are U.S. patents. These documents are designated as either Original (OR) or Cross-Reference (XR) placements.
The OR classification is based on the claims in the patents. Because claims define the novel disclosures in a patent, each claim is assigned a classification which is considered mandatory and primary. The remaining mandatory classifications are designated as cross-references (XR). Additional XR classifications may be designated for any unclaimes subject matter, which is novel and is of sufficient detail and clarity to be useful as a reference.
The USPC system also contains many foreign patents and pieces of non-patent literature. Until October 1, 1995, the USPTO classified the received foreign patent documents into the USPC system. Beginning in October 1995, newly published foreign patent documents were no longer classified onto USPC system.
Search Tool

To locate patents pertaining to a specific field of technology or science within the USPC System requires a good measure of judgement as well as the continuous and coordinated use of the following publications:

1. Index to the U.S. Patent Classification Systems
2. The Manual of Classification
3. Patent Classification Definitions
4. Classification Orders

The Index is particular useful for those lacking experience in using the classification system and those unfamiliar with the particular technology under consideration. It is arranged alphabetically with subheadings that can have four levels of indentation. Some headings will reference other related or preferred entries with a "(see�)" phrase. They may reference the notes to the Classification Definitions when these notes are particularly detailed or lucid on important distinctions not easily captures in the abbreviated entries of the index.

The Manual of Classification contains a collection of the class schedules, a list of the class titles in numerical order by class number and in alphabetical order, a list of the classes by Examining Groups, and a theoretical organization of classes into major groups. It includes 500 classes and covers all technology categories with 100,000+ subclasses among them.

The Patent Classification Definitions comprise statements of the scope embraced by each of the official classes, subclasses, and cross-reference art collections. Direction to related subject matter in other classes and subclasses is also included.

Classification Orders are issued throughout the year and contain information relating to U.S. patent classifications that are established or abolished as a result of reclassification projects. These orders are used to bridge the gap between the time a project issues and the time that regular search tools are updated to incluse the new information.

IV. Concordance between USPC and IPC

The U.S. Patent & Trademark Office has developed a concordance between its USPC system and the IPC. That is, the correspondence is a guide for relating the USPC System to the Seventh Edition of the IPC (IPC 7th). The United States Patent Classification To International Patent Classification Concordance is intended only as a guide or tool providing information which allows the user to quickly access the correct, general classification area of the IPC7th. Because of the differences in the philosophies of the two systems, these concordance tables are not always accurate and a complete one-to-one relationship has not been attained.
IPC/USPC Terminology Equivalents

IPC	USPC
Section	Discipline (Mechanical)
Class	Category of Classes (tools)
Subclass	Class
Group	Subclass
Main group	Mainline subclass
Subgroup	Indented subclass

The IPC system also hierarchically indents dependent titles and the titles are intended to be read in a manner similar to indented USPC titles. However, the IPC system does not have a single standard superiority rule similar to that of the USPC system. That is, the first occurring subclass of two coordinate subclasses in a Class is always superior in USPC. The IPC system instead utilizes either:

The subject matter proper for each group is restricted by all limitations to its scope imposed by the title of its IPC subclass, all higher level group titles under which it is indented, its own title, and relevant notes and references. The only exception is that IPC subclass or group titles that specify only a process, a product, or an apparatus category of invention may also include another category within their scope for its specific subject matter.
The correspondence indicated between the codes of the two systems should be used as a starting point for determining the final IPC 7th classification corresponding to a USPC classification. Although the concordance often seems to infer that the concorded classifications are equivalents, differences in placement rules and the interpretation of the scope of the subject matter claimed between the two systems makes such as a one-to-one translation rarely attainable. Therefore, the Concordance should not be used alone to identify the correct classification area of the IPC7th that corresponds to a classification area in the USPC. Concordance tables can be used to determine preliminary classification areas but reference to the class schedules is imperative.

IV. Conclusions

For the foregoing discussion, it is shown that IPC divides into 69,000 subdivisions and there are over 125,000 subdivisions for USPC. In term of depth of classification, USPC usually gives more information of what the invention is. On the other hand, in the IPC, an invention is mainly classified according to its "function". USPC, however, is not classified based on only the function but industry or use, effect or products, and structure as well. Therefore, USPC is categorized much more elaborately than IPC.

Due to the character of USPC, extremely narrow in focus, it is sometimes difficult for a person who is not in the state of the art to search by USPC. Extremely broad in focus for IPC makes searchers obtain many unrelated prior art in a crowded invention field while searching by IPC.

Though the USPTO has developed a concordance between its USPC system and the IPC, these concordance tables are not always accurate nor complete since the various classification systems are different and not all revised at the same frequency. Consequently, the Concordance should not be used alone to identify the correct classification area of the IPC 7th that corresponds to a classification area in the USPC.

The difference between national classification is so great and the concordance tables are not exactly correct. Additionally, to reclassify each of foreign patent documents according to its own national classification is inefficient. Using IPC and USPC, two major patent classification systems, is confusing for searchers. Therefore, establishing a uniform classification system or a good concordance system between IPC and USPC would be a welfare for people who doing patent searches.

Reference:

http://www.uspto.gov

http://www.wipo.int

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