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The U.S. patent classification or the international patent classification: Which system should the people's Republic of China adopt?
Xu Yi-Ping, Assistant Professor Shanghai Information Institute of Science and Technology, People’s Republic of China assisted by P. James Terragno*, Director, Office of Search Systems U.S. Patent and Trademark Office, Washington, D.C., U.S.A.
The U.S. Patent Classification or the International Patent Classification : Which System Should the People’s Republic of China Adopt? Summary
The philosophy, principle and structure of the US Patent Classification and of the International Patent Classification are discussed and compared. It is found that the IPC is easier for the public to use, and since it is internationally applied, it should be adopted by the People’s Republic of China. La philosophie, les principes et les structures de et de la classification internationale des brevets ressort que la CIB est plus facile a utiliser par le le plan international, elle devrait Gtre adoptee par
la classification americaine des brevets (CIB) sont discutes et cornpart%. I1 en public; et comme elle est employee sur la Ripublique populaire de Chine.
Die Philosophie, Prinzipien und Strukturen der US-Patentklassifikation und der Internationalen Patentklassifikation werden diskutiert und verglichen. Es stellt sich heraus, daR die IPC leichter durch die iiffentlichkeit zu benutzen ist; und da sie international angewendet wird, sollte sie von der Volksrepublik China angenommen werden.
Background The People’s Republic of China (PRC) is preparing to establish a patent system and a patent office. This preparation process includes missions by staff members from the PRC to various patent offices to study in detail the operation of these patent offices. The paper is an extract of a report prepared by a member of such a mission to the United States Patent and Trademark Office. The entire report has been submitted to the ., appropriate authorities m the PRC for their consideration and for their use in adopting or developing a patent classification system for the PRC.
Introduction Classification as a systematic arrangement or subdivision of subject matter lies at the foundation of the mental processes. Without the power of perceiving, recognizing resemblances, distinguishing differences in things, phenomena and notions, grouping them mentally according to those resemblances and differences, judgment would be impossible. Nor could reason be exercised in proceeding from the known to the unknown. A reasonable patent classification system is a logical arrangement of scientific and technical information and facilitates access to this information both for classifiers and searchers. With the extremely rapid development of science and technology, users need to get more and more information from patents, and patents as an intellectual property which is dedicated to the society by the inventor, should be available to more and more users when desired. So the main task in front of us is to make the information in patents as easily accessible as l
Mr. Terragno is now Vice President, Patent Information, of Pergamon International Information Corporation
World Patent Information 2 (1980)
possible to technologists using an appropriate patent classification system or improving an existing one. But a problem to be faced by us in making technological information from patents available to more users is that the different kinds of users want different kinds of information from patents; and all the needs have to be considered when choosing an appropriate patent classification system. For example, some users will use patents to review and comment on the state of the art by assembling, analyzing and making available meaningful data from patents. Others will be concerned primarily with improving their general knowledge of the art. Some will for commercial reasons want to know what their competitors are doing; they will require more detailed information than the first group. Others will look for full details of a new technique so that they can duplicate it; they will require even more detailed information. So it is certain that choosing a patent classification system to meet all those needs or looking for measures to make existing patent classification systems help solving so different problems is a very important matter. The U.S. Patent Classification System (USPCS) is .~ one of the most complete and systematic classifications in the world. The International Patent Classification (IPC) is the product of international cooperation in patent classification. It is very important to study and compare both patent classification systems to get more experience for choosing and improving our own patent classification system.
The U.S. Patent Classification
System
The search file of the U.S. Patent and Trademark Office (USPTO) a t present contains about 12.5 million U.S. patent documents, about 10 million foreign patent documents and approximately one million pieces of non-patent literature - a total of 2 3.5 million
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documents - and is growing at an annual rate of over 500 000 documents (1). HOW can such a huge technological information resource be useful if there is no systematic way to find what is needed? Let us assume that a scientist or a patent examiner was assigned the task of searching the entire USPTO search file. Further let us assume that he would spend one minute looking at each document and devote eight hours a day and seven days a week to his task. At that rate it would take him about 70 years just to look at every U.S. patent now in the file and another 60 years to search the foreign patent documents and the technical literature. Obviously, without a logical scheme of organization, such a vast file would be virtually useless. The USPCS was developed to make it possible to search the U.S. patent file efficiently.
The history of the U.S. Patent Classification System The USPCS has developed in roughly four stages; the initial stage, formation stage, completion stage and advancement stage. The initial
stage (1790
to 1867)
The beginning of U.S. patent classification can be traced to the middle of the nineteenth century. Although the U.S. Congress established a U.S. patent system in 1790, there were neither an available collection of prior patent documents, nor an accepted technique for making the required determination of novelty and utility at the time. In the beginning, all patents were filed chronologically. In 1830, the U.S. Congress authorized publication of a subject oriented patent listing; a patent list in groups was issued in 183 1 and a listing of 22 classes was issued in 1838. Without significant changes, this schedule of 22 classes was used until 1868. The formation
stage (1868
to 1897)
With the rapid growth of U.S. patent documents, (10 000 in 1836 to 80 000 in 1868), the United States adopted and gradually formed a new classification system which was influenced by the French and British patent classification. This new classification system formed the basis of the present USPCS as to structure and principles. The new system increased the number of classes from 22 to 26, dropped the miscellaneous grouping, provided for primary and secondary subdivisions within many classes, and adopted Roman numeral designations for the classes, Arabic numeral 126
designations for primary “sections” and capital letter designations for “subsections”. It further provided for third order subdivisions and included several “see” notations. Sections and subsections included alphabetical listsof items encompassed by the class title and class title subscript. The classes were also alphabetically arranged and, as before, bore no other relationship to each other. The 1868 USPCS was superseded in 1872 by a similar, but expanded one. There were now 165 classes and significantly more notes and subdivisions. These 165 classes created the framework upon which the present USPCS was built. Later there were some changes consisting of either intraclass changes, the addition of new classes or abolition of old classes. Until 1897 there were 215 classes, almost all of which were subdivided into alphabetically ordered subclasses with no cross-notes or other guides except an alphabetical index for all subclass titles keyed to a proper class title. In 1897, the classification was revised to include 226 classes. The completion
stage (1898
to 1965)
By 1898, the United States had reached the framework of a complete classification system. The U.S. Congress passed an act in 1898 which established the Classification Division of the USPTO and directed it to reclassify all prior art. Since then, starting with some Herculean labor by an untrained staff, the classes existing in 1898 were individually revised and modified - over a period spanning 67 years - consistent with a continually developing plan according to written guidelines and detailed class and subclass title definitions and notes. In addition to revising and modifying previously existing classes, many new classes were created during this period. The advancement
stage (1965
to present)
This last stage has been characterized by a systematic revision process to provide for new technological areas and to accommodate changes or growths in existing technological areas. This means that a number of new classes and subclasses are established each year and old classes and subclasses are changed or abolished. Annually three to four percent of the search file in the USPTO is affected by this revision process. When a class or subclass is revised, all of the documents are reclassified no matter how old; that is, the documents are placed in new or different classes or subclasses as required by the revision, and a new schedule and new definitions reflecting the revision are immediately
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published. The USPCS is in this respect a very dynamic system. This stage has also been characterized by increasing use of automated data processing techniques to assist the classification activities, especially since 1974. By using a computer data base, which contains an inventory of U.S. patents in each class and subclass, the USPTO is able to follow and monitor file growth and then decide which classes or subclasses are to be selected for reclassification. Analysis demonstrates that on a short term basis of a year or two, 30% of the patents granted relate to only 10% of the subclasses in the USPCS. This concentration of file activity is continuously changing in response to technological advancements. To identify the areas most frequently searched and/or inadequately classified, a project selection technique has been developed which involves interplay among objective data obtained from the computer record as to search activity, the professional judgement of classifiers and the views of examiners.
The philosophy and principles of the U.S. Patent Classification System The USPCS was developed to make the patent file a useful search tool. It provides for the storage and retrieval of documents used by a patent examiner in connection with the examination of patent applications. Accordingly, the system is exhaustive of all subject matter patentable under the U.S. patent laws. It is designed to allow a reasonably short and complete search to be made by examiners in their determination of patentability, and by inventors and others in their efforts relating to preexamination, state of the art, validity and infringement determination. Early U.S. patent classification was largely industry oriented. However, as U.S. patent law developed it became increasingly evident that this approach was not satisfactorily meeting the needs of the U.S. patent system. It did not parallel the path along which legal doctrine as to patentability was developing. As a result the system was rewamped and the concept of “proximate function” was adopted as the basis of U.S. patent classification. Under this concept devices of processes that inherently achieve similar results are classified together regardless of their stated use. Thus, all cutting machines are generally arranged together, be they for wood, metal, cheese or meat, because they share the proximate function of cutting. The obligatory classification of patents in the USPCS is based on claimed subject matter, that is, the claims in light of the disclosure. All U.S. patents must World Patent Information
have one and only one original classification. This original classification is based on the most comprehensive claim in the patent. The most comprehensive claim is defined as the one which encompasses more of the disclosed technical subject matter than any other; this claim is used, for classification purposes, as a summary of the whole technical disclosure. The patent may also have additional classifications, so-called cross-references. Nearly every patent document discloses subject matter other than that in the most comprehensive claim. This subject matter may be claimed in other claims or may not be claimed at all. If the subject matter is claimed in a claim other than the most comprehensive claim, then it is obligatory that the patent be cross-referenced into the proper subclass for that subject matter. Non-claimed subject matter may be classified at the discretion of the examiner or classifier. The USPCS has a precedence rule, known as a first place rule or a rule of superiority, which applies to all subclasses within each class. This precedence rule applies when different subclasses having the same indentation level within the same class are involved. The patent will then be classified in the subclass which comes highest in the schedule. Related to the first place rule is the fact that the relative position of a subclass in the schedule is important.
The International
Patent Classif ication System
The exponential growth of the volume of scientific and technological information generated in the world as well as the increasing complexity and interrelationship of problems facing each country’s plans for economic development make it important for different countries to share their knowledge, experience and other resources. This sharing will facilitate transfer of scientific and technological achievements and will make such achievements accessible on a mutually advantageous basis. The exchange of technological information is an essential prerequisite for developing and strengthening the national economic potential of any country, for bridging the technological gap between and within different countries and for furthering scientific and technological progress in the world. Patents are an important technological information resource. As technical literature, patents also represent a good medium for exchanging science and technology among different countries. Currently, about one million patent documents are published annually in the world. How can such a huge intellectual information resource be utilized? Clearly, this information has to be organized in a systematic arrangement by subject
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matter to facilitate its retrieval. If such an arrangement could be utilized and understood uniformly-by all countries it would be ideal. The International Patent Classification (IPC) is a means of obtaining, conceptually, an internationally uniform classification of patent documents dealing with any particular field of technology. It has as its primary purpose the establishment of an effective search tool for retrieving patent documents by patent examiners and members of the public. At present, there are thirty-seven patent offices which apply the IPC to its full extent to their published patent documents, that is, down to the finest subdivision of that classification. Eleven other offices and one regional office (The African Intellectual Property Organization) currently apply the IPC only down to the subclass level. The history and the structure of the IPC has recently been described in an article in this journal (2) (ed.).
The philosophy Classification
of the International
Patent
The IPC has been designed for the classification of patents of invention, and the subjects covered are therefore limited to those which are regarded by at least one country as proper to the field of patents. The IPC, like all patent classification systems, is intended to be used at a “pigeon hole” system, i.e., a system in which the documents themselves form the contents of the files and are used directly in searching procedures. In a sense, the IPC is a new and emerging patent classification system which has been influenced and is influenced by the national systems. Based on experiences gained from national classification systems, the IPC uses the combination of two main classification principles. In establishing a patent classification system, one of two main approaches has traditionally been followed. Under one the inventions are classified according to the branches of industry, “art”, of human activity to which they are characteristically relevant. This approach is usually termed “industry-oriented”, “art-oriented” or “applicationoriented”. The former German Patent Classification, which had a certain influence on the International Patent Classification, used this approach. Under the other approach inventions are classified according to the function to which they are characteristically relevant. This approach is usually termed “function-oriented”. The U.S. Patent Classification System of this nature. Under the IPC, inventions concerning the intrinsic nature or function of a thing which are independent of a particular field of use, or which technically are not 128
affected if statements about the field regarded, are referred to as function tions. Consequently, these inventions function-oriented places. Examples of are : B 01 D co7 F 16 K
-
G 0.5 B
-
I-I 03 K
-
of use are disoriented invenare classified in such IPC areas
Separation Organic chemistry Valves; tapes; cocks; actuating-floats’ devices for venting or aerating Control or regulating systems in general; functional elements of such systems, monitoring or testing arrangements for such system or elements Pulse technique
The intrinsic function of a mechanical valve, for example, is to close or to open a passage and this is determined by constructional or functional details or principles. The fact whether, in such a case, the valve is to operate for instance in a water pipe system or in a brewery pipe system transporting beer is without significance. Inventions concerning the particular use or application of an object where the object per se does not constitute the subject of the invention are referred to as application inventions. Consequently, these inventions are classified in application places. For example, the use of a chemical compound as a fertilizer or detergent is classified in the application place, i.e., the place for the fertilizer or detergent. The two approaches can hardly be applied in their theoretical purity. Some inventions disclose both intrinsic function and application; the IPC allows multiple classification in these cases. In fact, this combination of two main classification principles is the result of experience acquired by examiners whose daily work it is to compare inventions for which patent protection is claimed with similar inventions already disclosed in published patent documents. It is intended to make the system more convenient to use by examiners and the public.
Use of the IPC for retrieving technical information The IPC is intended for use in different types of searches, not only the novelty search which is the type most familiar to examiners in a patent office. Patentability or validity searches and infringement searches also have to be made by users of the system and this has some influence on its character and the way in which classifiers perform their duty.
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Comparison of the two patent classification systems The purpose of a patent classification system is to provide an effective tool for classifying as well as for retrieving patent documents. Thus, a comparison of such systems, to be valid, must be tempered by consideration of practical uses of the system. The general uses of a patent classification system may involve any or all of the following three categories: (a) the searching and retrieving from a file those documents that relate to a particular subject matter, (b) the filing and storing of patents in an orderly manner, and (c) the administrative assignment of patent applications for examination purposes. The first and second categories are intimately related since the basic purpose of the storage system is to facilitate the search and retrieval of the information contained therein. They are very important because these two categories determine whether the huge information sources of patent documents can be used effectively by those who need such information.
Structure In the USPCS, classes are structured using a basic scheme wherein most complex subject matter appears first in the classification schedule. A rule of superiority is utilized, i.e., among coordinate subclasses, the patent will be classified in that subclass which stands highest in the schedule of subclasses. The IPC also uses a precedence rule but only for some areas. This rule is a last place rule as opposed to a first place rule, or a rule of superiority. But there is no uniform structure or logical scheme adhered to when a classification schedule in the IPC is built. The USPCS contains about 355 classes with approximately 100 000 subclasses. It also a has a plant class with 89 subclasses and 39 design classes with 3548 subclasses. The IPC contains 8 sections, 118 classes, 617 subclasses including about 7000 main groups and approximately 47 000 subgroups. Both the USPCS and the IPC use a hierarchical structure for listing categories (subclasses in the USPCS and groups in the IPC).
Principles of classification The rules of the USPCS and the IPC both specify that technical subject matter be classified in substantially the same manner. Subject matter in both the USPCS and the IPC is classified as defined by the claims, with due regard to the description and the drawings. Both systems provide for multiple placement of a patent World Parent Information 2
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No. 3
Xu -
US
document using cross-referencing in the USPCS and multiple classification in the IPC. The primary basis of the USPCS is the concept of “proximate function”. This concept, “proximate function”, means that devices or processes that achieve similar results are classified together regardless of their stated use. The earlier editions of the IPC lean toward an “applicationoriented” system. This concept, “application-oriented “, means that inventions are classified according to the branches of industry, “art” or human activity. Each successive edition of the IPC has had “function-oriented” and “applicationsboth, the oriented ” categories. The USPCS is built empirically by a detailed analysis of the documents in a particular field of technology, and by setting out the differences among them. The USPCS is revised using examiners as well as professional classifiers. The classification is continually revised during development in accordance with what is learned from document placement. This assures that all subdivisions will be of reasonable size. The system is a dynamic one since all revisions are published as soon as practicable. The IPC has been built sometimes as a listing of concepts of what the classifiers and examiners conceived in theory to be all possible kinds of devices, processes and apparatuses without reference to actual patent documents. The IPC is revised largely on the basis of examiners’ suggested revisions, which are also sometimes theoretical, and through subsequent comments and meetings of experts from different countries. The IPC revision is then refined to the satisfaction of all parties involved. New IPC editions come out only every five years.
Reference tools Both the USPCS and the IPC have reference tools which help examiners and the public to use the system. These are the Manual of Classification (International Patent Classification). Index to Classification (Catchword Index), and the Development and Use of the USPCS (Guide to Use of IPC). However, the USPCS has an important additional reference tool, the Definitions. In the USPCS, the titles for subclasses are rather brief and detailed definitions are provided for each classification unit. In the IPC, the titles tend to be more explicit than those in the USPCS. In some cases, definition of certain terms are given in the IPC after the title of a section or class. Also “referral out” notes are provided to refer searchers to similar or related subject matter.
Patent Classification or IPC
129
International
aspects
The USPCS is a national patent classification system for the United States. Owing to its sophistication and completeness, some countries, Canada for example, adopt variations of the USPCS to classify their national patent documents. The IPC is being influenced by the USPCS more and more, especially in its structure and principles. However, the IPC is the only truly international patent classification system in the world. A comparative summary between the USPCS and the IPC is given in the table: Table USPCS
IPC
1. Structure is good for exam1. Structure is good for examination, particularly nation particularly if law if law includes inventive includes only novelty and if step as well as novelty. examination is based on industrial use. 2. Revision published every five 2. Revision is dynamic good for keeping pace years; facilitates storage and with technological develservice in public libraries opment and change. 3. The contents of all classes are defined and search is more complex but more precise using definitions.
3. No definitions of class contents - not as precise but longer titles help.
4. More difficult to use by 4. Easier to use by public bepublic because of comcause search is not as complex plexity and unfamiliarity and because system is “apwith “function-oriented” plication-oriented.” concept. 5. Numbering system some-15. More orderly and better structured coding system times confusing for users. 6. USPTO is only office to 6. IPC symbols assigned by assign symbols to U.S. 37 patent offices. patents and is only office to use system for searching all patent documents.
Conclusions The USPCS is a complete, well developed and well defined scheme for classifying and searching patent documents. Its sophisticated structure and principles have influenced not only the IPC but also various national patent classification systems. It is clearly a system which must be given consideration, as it has in this paper, by the PRC if the new patent system soon to be implemented includes examination for inventive step (obviousness) as well as novelty. 130
The system is a formidable one and one especially effective for examiners to conduct examinations for novelty and innovative step. It is useful as an administrative aid for the U.S. office to assign patent . . applications to the correct examination area. It is an exhaustively defined system: this results in fewer ambiguities of both placement and search than a system which is less well defined. Its continuous revision procedure enables users to keep up reasonably well with new, developing and growing technological areas. The revision procedure, being a pragmatic one based on document placement, results in a more balanced document distribution among its categories. The USPCS has two primary drawbacks. First, it is a difficult system for the public at large to use. This is so because of its complexity and sophistication. It is also due in part to the numbering scheme for classes and subclasses. No systematic numbering scheme is employed and to the uninitiated, the scheme used can be confusing. This problem can be overcome by conducting extensive training for users and by adopting an improved numbering system. The second problem with the USPCS is that it is not an international system. The USPTO is the only patent office which uses the USPCS for searching all patent documents; and, what is more important, it is the only patent office in the world which assigns USPCS symbols to its patents. The Canadian Patent Classification System is similar but not identical to the U.S. system. It is not probable that the USPCS will become an international system, since no ther patent offices have expressed an interest in using the USPCS or assigning its symbols to their documents. The IPC has as its main advantage the fact that it is an international system and is based on an international agreement, the Strasbourg Agreement. It is administered by an international UN organization, WIPO. It is revised on an international, cooperative basis. Thirtyseven patent offices assign IPC symbols to their patent documents. Many patent offices throughout the world use the IPC for search purposes including almost all offices in Europe. Of the six international searching authorities under the Patent Cooperation Treaty, five of them (Austria, Japan, Soviet Union, Sweden, and the European Patent Office) use the IPC for search purposes. The IPC is an easier system, generally speaking, for the public to use. Its relative lack of complexity and its presentation facilitate use by the uninitiated. At the same time, its categories tend to be more ambiguous due to the absence of definitions. The IPC suffers from some technical problems
World Patent Information 2 (1980) No. 3 Xu - US Patent Classification or IPC
which are of potential importance to the PRC. Primary among these problems are (a) the fact that its revisions are not published on a continuous basis and (b) that its categories are formulated on a theoretical and not a pragmatic basis. The first problem leads to lags in publishing new categories for new or rapidly growing technologies. The second problem results in imbalances in the number of documents in some categories and insufficient breakdowns for some areas of technology. These problems can be overcome either by using new revisions of the IPC prior to their publication in a formal edition of the IPC or by further breakdowns of IPC categories to meet needs of the national office. The European Patent Office makes use of the latter practice. All factors considered the PRC should adopt the IPC as its primary basis of patent classification and search. First of all for reasons of economy. Thirtyseven patent offices assign IPC symbols to their patent documents. When these documents are received by the PRC and stored in its search file, there will be no need to reclassify them according to a different system, whereas substantial resources would be required to classify them according to the USPCS or any other national system. In addition, the IPC is truly an international system, and closer than any other at present to the ideal of one common patent classification system for the world. This ideal will be difficult to achieve but progress continues and the PRC will have the opportunity to participate in this progress. This will prove to be valuable since it will enable the PRC to be an active participant in the international patent documentation and information activities. Bibliography Assessment and Fore1. A. C. Mamor et al.: The Technology cast Program of the United States Patent and Trademark Office - World Patent Information, Vol. 1, No. 1,~. 1523, July 1979. The International Patent Classifica2. P. Claus, B. Hansson: tion - World Patent Information, Vol. 2,No. 1, p. 13-20, January 1980. 3. P. J. Terragno, “Patents as Technical Literature”, IEEE Trans. Prof. Commun. Vol. PC-22 No. 2, p. 101, June 1979. 4. K. J. Dood, “The U.S. Patent Classification System”, IEEE Trans. Prof. Commun. Vol. PC-22 No. 2,~. 95, June 1979. 5. H. Skolnik, “Historical Aspects of Patent Systems”, IEEE Trans. Prof. Commun. Vol. PC-22 No. 2, p. 59. June 1979. Office, “Development and Use 6. U.S. Patent and Trademark of Patent Classification Systems”, Jan. 1966. 7. B. Hansson, “History of the IPC and WIPO’s Activities in the Field of the IPC”, Seminar on Patent Information and the IPC in Beijing, November 12 to 20, 1979. World Patent
Information
2 (1980)
No. 3 Xu - US Patent
to the ‘Advice to Classifiers’ and 8. A. Sugden, “Introduction Seminar on Patent Information the ‘Advice to Searchers”‘, and the IPC in Beijing, November 12 to 30, 1979. 9. P. J. Terragno, “The U.S. Patent Classification System and Its Associated Publications”, Seminar on Patent Information and the IPC in Beijing, November 12 to 30, 1979. and Information”, J. Chem. Inf. 10.M. J. Marcus, “Patents Comput. Sci. Vol. 18,No. 2,197s. 11. A. C. Marmor, “Characteristics and Volume of Patent InInt. Symposium Patent Information and Doformation”, cumentation, Munich,May 16-18.1977. 12.F. A. Sviridov, “Patent Information Activities of WIPO”, Int. Symposium Patent Information and Documentation, Munich,May 16-18, 1977. and Application 13. E. Herbig and K. H. Ulmer, “Introduction of the IPC of the German Patent Office’, Int. Symposium Patent Information and Documentation, Munich, May 16-18,1977. 14. G. Gehring, “Critical Remarks on the Availability of patent Information for the Public Today and in the Future”. Int. Symposium Patent Information and Documentation, Munich, May 16-18,1977. 15. M. G. Harman, “Information Retrieval from Patents”, Int. Symposium Patent Information and Documentation, Munich,May 16-18, 1977. 16.T. S. Eisenschitz, “Reasons for Inconsistencies in the Use of the IPC”, Int. Classification 6 (1979) No. 1, p. 26. 17.B. Hansson, “The IPC Philosophy and Structure”, Seminar on Patent Information and the IPC in Beijing, November 12 to 30.1979. 18. Kurt Haertel, “The IPC: Basic Structure and Characteristics; Use of the IPC; Program of the German Patent Office for IPC Implementation”, WIPO, MOSCOW Symposium, October 7 to 12, 1974. 19. U.S. Patent and Trademark Office, “The U.S. Patent Classification and the IPC - A Comparison,” Internal Memorandum, Oct. 6.1978. Patent Classification - General In20. WIPO, “International formation”, WIPO Publication No. 409 (E), 1975. 21.F. Peleat, “General Outline of the Int. Cl. 3rd Edition”, April 1976. 22. WIPO, “General Information on the IPC”, Training Course for Developing Countries, Geneva, May 5 fo 9, 1975. 23.W. L. J. Ennerst, “History and Development of the International Classification of Patents”, Seminar for Officers Concerned with the Training of Personnel in the Use of the IPC, Hague, May 1974. 24.J. J. Hillen, “Principles of the International Classification of Patents”, Seminar for Officers Concerned with the Training of Personnel in the Use of the IPC, The Hague,May 1974. 25. R. Bare, “Searching and its Practical Problems”, Seminar .for Officers Concerned with the Training of Personnel in the Use of the IPC, The Hague, May 1974.
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The U.S. Patent Classification or the International Patent Classification : Which System Should the People’s Republic of China Adopt? Summary
The philosophy, principle and structure of the US Patent Classification and of the International Patent Classification are discussed and compared. It is found that the IPC is easier for the public to use, and since it is internationally applied, it should be adopted by the People’s Republic of China. La philosophie, les principes et les structures de et de la classification internationale des brevets ressort que la CIB est plus facile a utiliser par le le plan international, elle devrait Gtre adoptee par
la classification americaine des brevets (CIB) sont discutes et cornpart%. I1 en public; et comme elle est employee sur la Ripublique populaire de Chine.
Die Philosophie, Prinzipien und Strukturen der US-Patentklassifikation und der Internationalen Patentklassifikation werden diskutiert und verglichen. Es stellt sich heraus, daR die IPC leichter durch die iiffentlichkeit zu benutzen ist; und da sie international angewendet wird, sollte sie von der Volksrepublik China angenommen werden.
Background The People’s Republic of China (PRC) is preparing to establish a patent system and a patent office. This preparation process includes missions by staff members from the PRC to various patent offices to study in detail the operation of these patent offices. The paper is an extract of a report prepared by a member of such a mission to the United States Patent and Trademark Office. The entire report has been submitted to the ., appropriate authorities m the PRC for their consideration and for their use in adopting or developing a patent classification system for the PRC.
Introduction Classification as a systematic arrangement or subdivision of subject matter lies at the foundation of the mental processes. Without the power of perceiving, recognizing resemblances, distinguishing differences in things, phenomena and notions, grouping them mentally according to those resemblances and differences, judgment would be impossible. Nor could reason be exercised in proceeding from the known to the unknown. A reasonable patent classification system is a logical arrangement of scientific and technical information and facilitates access to this information both for classifiers and searchers. With the extremely rapid development of science and technology, users need to get more and more information from patents, and patents as an intellectual property which is dedicated to the society by the inventor, should be available to more and more users when desired. So the main task in front of us is to make the information in patents as easily accessible as l
Mr. Terragno is now Vice President, Patent Information, of Pergamon International Information Corporation
World Patent Information 2 (1980)
possible to technologists using an appropriate patent classification system or improving an existing one. But a problem to be faced by us in making technological information from patents available to more users is that the different kinds of users want different kinds of information from patents; and all the needs have to be considered when choosing an appropriate patent classification system. For example, some users will use patents to review and comment on the state of the art by assembling, analyzing and making available meaningful data from patents. Others will be concerned primarily with improving their general knowledge of the art. Some will for commercial reasons want to know what their competitors are doing; they will require more detailed information than the first group. Others will look for full details of a new technique so that they can duplicate it; they will require even more detailed information. So it is certain that choosing a patent classification system to meet all those needs or looking for measures to make existing patent classification systems help solving so different problems is a very important matter. The U.S. Patent Classification System (USPCS) is .~ one of the most complete and systematic classifications in the world. The International Patent Classification (IPC) is the product of international cooperation in patent classification. It is very important to study and compare both patent classification systems to get more experience for choosing and improving our own patent classification system.
The U.S. Patent Classification
System
The search file of the U.S. Patent and Trademark Office (USPTO) a t present contains about 12.5 million U.S. patent documents, about 10 million foreign patent documents and approximately one million pieces of non-patent literature - a total of 2 3.5 million
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documents - and is growing at an annual rate of over 500 000 documents (1). HOW can such a huge technological information resource be useful if there is no systematic way to find what is needed? Let us assume that a scientist or a patent examiner was assigned the task of searching the entire USPTO search file. Further let us assume that he would spend one minute looking at each document and devote eight hours a day and seven days a week to his task. At that rate it would take him about 70 years just to look at every U.S. patent now in the file and another 60 years to search the foreign patent documents and the technical literature. Obviously, without a logical scheme of organization, such a vast file would be virtually useless. The USPCS was developed to make it possible to search the U.S. patent file efficiently.
The history of the U.S. Patent Classification System The USPCS has developed in roughly four stages; the initial stage, formation stage, completion stage and advancement stage. The initial
stage (1790
to 1867)
The beginning of U.S. patent classification can be traced to the middle of the nineteenth century. Although the U.S. Congress established a U.S. patent system in 1790, there were neither an available collection of prior patent documents, nor an accepted technique for making the required determination of novelty and utility at the time. In the beginning, all patents were filed chronologically. In 1830, the U.S. Congress authorized publication of a subject oriented patent listing; a patent list in groups was issued in 183 1 and a listing of 22 classes was issued in 1838. Without significant changes, this schedule of 22 classes was used until 1868. The formation
stage (1868
to 1897)
With the rapid growth of U.S. patent documents, (10 000 in 1836 to 80 000 in 1868), the United States adopted and gradually formed a new classification system which was influenced by the French and British patent classification. This new classification system formed the basis of the present USPCS as to structure and principles. The new system increased the number of classes from 22 to 26, dropped the miscellaneous grouping, provided for primary and secondary subdivisions within many classes, and adopted Roman numeral designations for the classes, Arabic numeral 126
designations for primary “sections” and capital letter designations for “subsections”. It further provided for third order subdivisions and included several “see” notations. Sections and subsections included alphabetical listsof items encompassed by the class title and class title subscript. The classes were also alphabetically arranged and, as before, bore no other relationship to each other. The 1868 USPCS was superseded in 1872 by a similar, but expanded one. There were now 165 classes and significantly more notes and subdivisions. These 165 classes created the framework upon which the present USPCS was built. Later there were some changes consisting of either intraclass changes, the addition of new classes or abolition of old classes. Until 1897 there were 215 classes, almost all of which were subdivided into alphabetically ordered subclasses with no cross-notes or other guides except an alphabetical index for all subclass titles keyed to a proper class title. In 1897, the classification was revised to include 226 classes. The completion
stage (1898
to 1965)
By 1898, the United States had reached the framework of a complete classification system. The U.S. Congress passed an act in 1898 which established the Classification Division of the USPTO and directed it to reclassify all prior art. Since then, starting with some Herculean labor by an untrained staff, the classes existing in 1898 were individually revised and modified - over a period spanning 67 years - consistent with a continually developing plan according to written guidelines and detailed class and subclass title definitions and notes. In addition to revising and modifying previously existing classes, many new classes were created during this period. The advancement
stage (1965
to present)
This last stage has been characterized by a systematic revision process to provide for new technological areas and to accommodate changes or growths in existing technological areas. This means that a number of new classes and subclasses are established each year and old classes and subclasses are changed or abolished. Annually three to four percent of the search file in the USPTO is affected by this revision process. When a class or subclass is revised, all of the documents are reclassified no matter how old; that is, the documents are placed in new or different classes or subclasses as required by the revision, and a new schedule and new definitions reflecting the revision are immediately
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published. The USPCS is in this respect a very dynamic system. This stage has also been characterized by increasing use of automated data processing techniques to assist the classification activities, especially since 1974. By using a computer data base, which contains an inventory of U.S. patents in each class and subclass, the USPTO is able to follow and monitor file growth and then decide which classes or subclasses are to be selected for reclassification. Analysis demonstrates that on a short term basis of a year or two, 30% of the patents granted relate to only 10% of the subclasses in the USPCS. This concentration of file activity is continuously changing in response to technological advancements. To identify the areas most frequently searched and/or inadequately classified, a project selection technique has been developed which involves interplay among objective data obtained from the computer record as to search activity, the professional judgement of classifiers and the views of examiners.
The philosophy and principles of the U.S. Patent Classification System The USPCS was developed to make the patent file a useful search tool. It provides for the storage and retrieval of documents used by a patent examiner in connection with the examination of patent applications. Accordingly, the system is exhaustive of all subject matter patentable under the U.S. patent laws. It is designed to allow a reasonably short and complete search to be made by examiners in their determination of patentability, and by inventors and others in their efforts relating to preexamination, state of the art, validity and infringement determination. Early U.S. patent classification was largely industry oriented. However, as U.S. patent law developed it became increasingly evident that this approach was not satisfactorily meeting the needs of the U.S. patent system. It did not parallel the path along which legal doctrine as to patentability was developing. As a result the system was rewamped and the concept of “proximate function” was adopted as the basis of U.S. patent classification. Under this concept devices of processes that inherently achieve similar results are classified together regardless of their stated use. Thus, all cutting machines are generally arranged together, be they for wood, metal, cheese or meat, because they share the proximate function of cutting. The obligatory classification of patents in the USPCS is based on claimed subject matter, that is, the claims in light of the disclosure. All U.S. patents must World Patent Information
have one and only one original classification. This original classification is based on the most comprehensive claim in the patent. The most comprehensive claim is defined as the one which encompasses more of the disclosed technical subject matter than any other; this claim is used, for classification purposes, as a summary of the whole technical disclosure. The patent may also have additional classifications, so-called cross-references. Nearly every patent document discloses subject matter other than that in the most comprehensive claim. This subject matter may be claimed in other claims or may not be claimed at all. If the subject matter is claimed in a claim other than the most comprehensive claim, then it is obligatory that the patent be cross-referenced into the proper subclass for that subject matter. Non-claimed subject matter may be classified at the discretion of the examiner or classifier. The USPCS has a precedence rule, known as a first place rule or a rule of superiority, which applies to all subclasses within each class. This precedence rule applies when different subclasses having the same indentation level within the same class are involved. The patent will then be classified in the subclass which comes highest in the schedule. Related to the first place rule is the fact that the relative position of a subclass in the schedule is important.
The International
Patent Classif ication System
The exponential growth of the volume of scientific and technological information generated in the world as well as the increasing complexity and interrelationship of problems facing each country’s plans for economic development make it important for different countries to share their knowledge, experience and other resources. This sharing will facilitate transfer of scientific and technological achievements and will make such achievements accessible on a mutually advantageous basis. The exchange of technological information is an essential prerequisite for developing and strengthening the national economic potential of any country, for bridging the technological gap between and within different countries and for furthering scientific and technological progress in the world. Patents are an important technological information resource. As technical literature, patents also represent a good medium for exchanging science and technology among different countries. Currently, about one million patent documents are published annually in the world. How can such a huge intellectual information resource be utilized? Clearly, this information has to be organized in a systematic arrangement by subject
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matter to facilitate its retrieval. If such an arrangement could be utilized and understood uniformly-by all countries it would be ideal. The International Patent Classification (IPC) is a means of obtaining, conceptually, an internationally uniform classification of patent documents dealing with any particular field of technology. It has as its primary purpose the establishment of an effective search tool for retrieving patent documents by patent examiners and members of the public. At present, there are thirty-seven patent offices which apply the IPC to its full extent to their published patent documents, that is, down to the finest subdivision of that classification. Eleven other offices and one regional office (The African Intellectual Property Organization) currently apply the IPC only down to the subclass level. The history and the structure of the IPC has recently been described in an article in this journal (2) (ed.).
The philosophy Classification
of the International
Patent
The IPC has been designed for the classification of patents of invention, and the subjects covered are therefore limited to those which are regarded by at least one country as proper to the field of patents. The IPC, like all patent classification systems, is intended to be used at a “pigeon hole” system, i.e., a system in which the documents themselves form the contents of the files and are used directly in searching procedures. In a sense, the IPC is a new and emerging patent classification system which has been influenced and is influenced by the national systems. Based on experiences gained from national classification systems, the IPC uses the combination of two main classification principles. In establishing a patent classification system, one of two main approaches has traditionally been followed. Under one the inventions are classified according to the branches of industry, “art”, of human activity to which they are characteristically relevant. This approach is usually termed “industry-oriented”, “art-oriented” or “applicationoriented”. The former German Patent Classification, which had a certain influence on the International Patent Classification, used this approach. Under the other approach inventions are classified according to the function to which they are characteristically relevant. This approach is usually termed “function-oriented”. The U.S. Patent Classification System of this nature. Under the IPC, inventions concerning the intrinsic nature or function of a thing which are independent of a particular field of use, or which technically are not 128
affected if statements about the field regarded, are referred to as function tions. Consequently, these inventions function-oriented places. Examples of are : B 01 D co7 F 16 K
-
G 0.5 B
-
I-I 03 K
-
of use are disoriented invenare classified in such IPC areas
Separation Organic chemistry Valves; tapes; cocks; actuating-floats’ devices for venting or aerating Control or regulating systems in general; functional elements of such systems, monitoring or testing arrangements for such system or elements Pulse technique
The intrinsic function of a mechanical valve, for example, is to close or to open a passage and this is determined by constructional or functional details or principles. The fact whether, in such a case, the valve is to operate for instance in a water pipe system or in a brewery pipe system transporting beer is without significance. Inventions concerning the particular use or application of an object where the object per se does not constitute the subject of the invention are referred to as application inventions. Consequently, these inventions are classified in application places. For example, the use of a chemical compound as a fertilizer or detergent is classified in the application place, i.e., the place for the fertilizer or detergent. The two approaches can hardly be applied in their theoretical purity. Some inventions disclose both intrinsic function and application; the IPC allows multiple classification in these cases. In fact, this combination of two main classification principles is the result of experience acquired by examiners whose daily work it is to compare inventions for which patent protection is claimed with similar inventions already disclosed in published patent documents. It is intended to make the system more convenient to use by examiners and the public.
Use of the IPC for retrieving technical information The IPC is intended for use in different types of searches, not only the novelty search which is the type most familiar to examiners in a patent office. Patentability or validity searches and infringement searches also have to be made by users of the system and this has some influence on its character and the way in which classifiers perform their duty.
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Comparison of the two patent classification systems The purpose of a patent classification system is to provide an effective tool for classifying as well as for retrieving patent documents. Thus, a comparison of such systems, to be valid, must be tempered by consideration of practical uses of the system. The general uses of a patent classification system may involve any or all of the following three categories: (a) the searching and retrieving from a file those documents that relate to a particular subject matter, (b) the filing and storing of patents in an orderly manner, and (c) the administrative assignment of patent applications for examination purposes. The first and second categories are intimately related since the basic purpose of the storage system is to facilitate the search and retrieval of the information contained therein. They are very important because these two categories determine whether the huge information sources of patent documents can be used effectively by those who need such information.
Structure In the USPCS, classes are structured using a basic scheme wherein most complex subject matter appears first in the classification schedule. A rule of superiority is utilized, i.e., among coordinate subclasses, the patent will be classified in that subclass which stands highest in the schedule of subclasses. The IPC also uses a precedence rule but only for some areas. This rule is a last place rule as opposed to a first place rule, or a rule of superiority. But there is no uniform structure or logical scheme adhered to when a classification schedule in the IPC is built. The USPCS contains about 355 classes with approximately 100 000 subclasses. It also a has a plant class with 89 subclasses and 39 design classes with 3548 subclasses. The IPC contains 8 sections, 118 classes, 617 subclasses including about 7000 main groups and approximately 47 000 subgroups. Both the USPCS and the IPC use a hierarchical structure for listing categories (subclasses in the USPCS and groups in the IPC).
Principles of classification The rules of the USPCS and the IPC both specify that technical subject matter be classified in substantially the same manner. Subject matter in both the USPCS and the IPC is classified as defined by the claims, with due regard to the description and the drawings. Both systems provide for multiple placement of a patent World Parent Information 2
(1980)
No. 3
Xu -
US
document using cross-referencing in the USPCS and multiple classification in the IPC. The primary basis of the USPCS is the concept of “proximate function”. This concept, “proximate function”, means that devices or processes that achieve similar results are classified together regardless of their stated use. The earlier editions of the IPC lean toward an “applicationoriented” system. This concept, “application-oriented “, means that inventions are classified according to the branches of industry, “art” or human activity. Each successive edition of the IPC has had “function-oriented” and “applicationsboth, the oriented ” categories. The USPCS is built empirically by a detailed analysis of the documents in a particular field of technology, and by setting out the differences among them. The USPCS is revised using examiners as well as professional classifiers. The classification is continually revised during development in accordance with what is learned from document placement. This assures that all subdivisions will be of reasonable size. The system is a dynamic one since all revisions are published as soon as practicable. The IPC has been built sometimes as a listing of concepts of what the classifiers and examiners conceived in theory to be all possible kinds of devices, processes and apparatuses without reference to actual patent documents. The IPC is revised largely on the basis of examiners’ suggested revisions, which are also sometimes theoretical, and through subsequent comments and meetings of experts from different countries. The IPC revision is then refined to the satisfaction of all parties involved. New IPC editions come out only every five years.
Reference tools Both the USPCS and the IPC have reference tools which help examiners and the public to use the system. These are the Manual of Classification (International Patent Classification). Index to Classification (Catchword Index), and the Development and Use of the USPCS (Guide to Use of IPC). However, the USPCS has an important additional reference tool, the Definitions. In the USPCS, the titles for subclasses are rather brief and detailed definitions are provided for each classification unit. In the IPC, the titles tend to be more explicit than those in the USPCS. In some cases, definition of certain terms are given in the IPC after the title of a section or class. Also “referral out” notes are provided to refer searchers to similar or related subject matter.
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International
aspects
The USPCS is a national patent classification system for the United States. Owing to its sophistication and completeness, some countries, Canada for example, adopt variations of the USPCS to classify their national patent documents. The IPC is being influenced by the USPCS more and more, especially in its structure and principles. However, the IPC is the only truly international patent classification system in the world. A comparative summary between the USPCS and the IPC is given in the table: Table USPCS
IPC
1. Structure is good for exam1. Structure is good for examination, particularly nation particularly if law if law includes inventive includes only novelty and if step as well as novelty. examination is based on industrial use. 2. Revision published every five 2. Revision is dynamic good for keeping pace years; facilitates storage and with technological develservice in public libraries opment and change. 3. The contents of all classes are defined and search is more complex but more precise using definitions.
3. No definitions of class contents - not as precise but longer titles help.
4. More difficult to use by 4. Easier to use by public bepublic because of comcause search is not as complex plexity and unfamiliarity and because system is “apwith “function-oriented” plication-oriented.” concept. 5. Numbering system some-15. More orderly and better structured coding system times confusing for users. 6. USPTO is only office to 6. IPC symbols assigned by assign symbols to U.S. 37 patent offices. patents and is only office to use system for searching all patent documents.
Conclusions The USPCS is a complete, well developed and well defined scheme for classifying and searching patent documents. Its sophisticated structure and principles have influenced not only the IPC but also various national patent classification systems. It is clearly a system which must be given consideration, as it has in this paper, by the PRC if the new patent system soon to be implemented includes examination for inventive step (obviousness) as well as novelty. 130
The system is a formidable one and one especially effective for examiners to conduct examinations for novelty and innovative step. It is useful as an administrative aid for the U.S. office to assign patent . . applications to the correct examination area. It is an exhaustively defined system: this results in fewer ambiguities of both placement and search than a system which is less well defined. Its continuous revision procedure enables users to keep up reasonably well with new, developing and growing technological areas. The revision procedure, being a pragmatic one based on document placement, results in a more balanced document distribution among its categories. The USPCS has two primary drawbacks. First, it is a difficult system for the public at large to use. This is so because of its complexity and sophistication. It is also due in part to the numbering scheme for classes and subclasses. No systematic numbering scheme is employed and to the uninitiated, the scheme used can be confusing. This problem can be overcome by conducting extensive training for users and by adopting an improved numbering system. The second problem with the USPCS is that it is not an international system. The USPTO is the only patent office which uses the USPCS for searching all patent documents; and, what is more important, it is the only patent office in the world which assigns USPCS symbols to its patents. The Canadian Patent Classification System is similar but not identical to the U.S. system. It is not probable that the USPCS will become an international system, since no ther patent offices have expressed an interest in using the USPCS or assigning its symbols to their documents. The IPC has as its main advantage the fact that it is an international system and is based on an international agreement, the Strasbourg Agreement. It is administered by an international UN organization, WIPO. It is revised on an international, cooperative basis. Thirtyseven patent offices assign IPC symbols to their patent documents. Many patent offices throughout the world use the IPC for search purposes including almost all offices in Europe. Of the six international searching authorities under the Patent Cooperation Treaty, five of them (Austria, Japan, Soviet Union, Sweden, and the European Patent Office) use the IPC for search purposes. The IPC is an easier system, generally speaking, for the public to use. Its relative lack of complexity and its presentation facilitate use by the uninitiated. At the same time, its categories tend to be more ambiguous due to the absence of definitions. The IPC suffers from some technical problems
World Patent Information 2 (1980) No. 3 Xu - US Patent Classification or IPC
which are of potential importance to the PRC. Primary among these problems are (a) the fact that its revisions are not published on a continuous basis and (b) that its categories are formulated on a theoretical and not a pragmatic basis. The first problem leads to lags in publishing new categories for new or rapidly growing technologies. The second problem results in imbalances in the number of documents in some categories and insufficient breakdowns for some areas of technology. These problems can be overcome either by using new revisions of the IPC prior to their publication in a formal edition of the IPC or by further breakdowns of IPC categories to meet needs of the national office. The European Patent Office makes use of the latter practice. All factors considered the PRC should adopt the IPC as its primary basis of patent classification and search. First of all for reasons of economy. Thirtyseven patent offices assign IPC symbols to their patent documents. When these documents are received by the PRC and stored in its search file, there will be no need to reclassify them according to a different system, whereas substantial resources would be required to classify them according to the USPCS or any other national system. In addition, the IPC is truly an international system, and closer than any other at present to the ideal of one common patent classification system for the world. This ideal will be difficult to achieve but progress continues and the PRC will have the opportunity to participate in this progress. This will prove to be valuable since it will enable the PRC to be an active participant in the international patent documentation and information activities. Bibliography Assessment and Fore1. A. C. Mamor et al.: The Technology cast Program of the United States Patent and Trademark Office - World Patent Information, Vol. 1, No. 1,~. 1523, July 1979. The International Patent Classifica2. P. Claus, B. Hansson: tion - World Patent Information, Vol. 2,No. 1, p. 13-20, January 1980. 3. P. J. Terragno, “Patents as Technical Literature”, IEEE Trans. Prof. Commun. Vol. PC-22 No. 2, p. 101, June 1979. 4. K. J. Dood, “The U.S. Patent Classification System”, IEEE Trans. Prof. Commun. Vol. PC-22 No. 2,~. 95, June 1979. 5. H. Skolnik, “Historical Aspects of Patent Systems”, IEEE Trans. Prof. Commun. Vol. PC-22 No. 2, p. 59. June 1979. Office, “Development and Use 6. U.S. Patent and Trademark of Patent Classification Systems”, Jan. 1966. 7. B. Hansson, “History of the IPC and WIPO’s Activities in the Field of the IPC”, Seminar on Patent Information and the IPC in Beijing, November 12 to 20, 1979. World Patent
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No. 3 Xu - US Patent
to the ‘Advice to Classifiers’ and 8. A. Sugden, “Introduction Seminar on Patent Information the ‘Advice to Searchers”‘, and the IPC in Beijing, November 12 to 30, 1979. 9. P. J. Terragno, “The U.S. Patent Classification System and Its Associated Publications”, Seminar on Patent Information and the IPC in Beijing, November 12 to 30, 1979. and Information”, J. Chem. Inf. 10.M. J. Marcus, “Patents Comput. Sci. Vol. 18,No. 2,197s. 11. A. C. Marmor, “Characteristics and Volume of Patent InInt. Symposium Patent Information and Doformation”, cumentation, Munich,May 16-18.1977. 12.F. A. Sviridov, “Patent Information Activities of WIPO”, Int. Symposium Patent Information and Documentation, Munich,May 16-18, 1977. and Application 13. E. Herbig and K. H. Ulmer, “Introduction of the IPC of the German Patent Office’, Int. Symposium Patent Information and Documentation, Munich, May 16-18,1977. 14. G. Gehring, “Critical Remarks on the Availability of patent Information for the Public Today and in the Future”. Int. Symposium Patent Information and Documentation, Munich, May 16-18,1977. 15. M. G. Harman, “Information Retrieval from Patents”, Int. Symposium Patent Information and Documentation, Munich,May 16-18, 1977. 16.T. S. Eisenschitz, “Reasons for Inconsistencies in the Use of the IPC”, Int. Classification 6 (1979) No. 1, p. 26. 17.B. Hansson, “The IPC Philosophy and Structure”, Seminar on Patent Information and the IPC in Beijing, November 12 to 30.1979. 18. Kurt Haertel, “The IPC: Basic Structure and Characteristics; Use of the IPC; Program of the German Patent Office for IPC Implementation”, WIPO, MOSCOW Symposium, October 7 to 12, 1974. 19. U.S. Patent and Trademark Office, “The U.S. Patent Classification and the IPC - A Comparison,” Internal Memorandum, Oct. 6.1978. Patent Classification - General In20. WIPO, “International formation”, WIPO Publication No. 409 (E), 1975. 21.F. Peleat, “General Outline of the Int. Cl. 3rd Edition”, April 1976. 22. WIPO, “General Information on the IPC”, Training Course for Developing Countries, Geneva, May 5 fo 9, 1975. 23.W. L. J. Ennerst, “History and Development of the International Classification of Patents”, Seminar for Officers Concerned with the Training of Personnel in the Use of the IPC, Hague, May 1974. 24.J. J. Hillen, “Principles of the International Classification of Patents”, Seminar for Officers Concerned with the Training of Personnel in the Use of the IPC, The Hague,May 1974. 25. R. Bare, “Searching and its Practical Problems”, Seminar .for Officers Concerned with the Training of Personnel in the Use of the IPC, The Hague, May 1974.
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