Dewey Decimal Classification

The Dewey Decimal Classification (DDC), or Dewey Decimal System, is a proprietary library classification system first published in the United States by Melvil Dewey in 1876. It has been revised and expanded through 23 major editions, the latest issued in 2011, and has grown from a four-page pamphlet in 1876 with less than one thousand classes to a four volume set. It is also available in an abridged version suitable for smaller libraries. It is currently maintained by the Online Computer Library Center (OCLC), a library research center. OCLC licenses access to an online version, WebDewey, for catalogers, and has an experimental linked data version on the Web with open access.

The Decimal Classification introduced the concepts of relative location and relative index which allow new books to be added to a library in their appropriate location based on subject. Libraries previously had given books permanent shelf locations that were related to the order of acquisition rather than topic. The classification's notation makes use of three-digit Arabic numerals for main classes, with fractional decimals allowing expansion for further detail. A library assigns a classification number that unambiguously locates a particular volume in a position relative to other books in the library based on its subject matter. This makes it possible to find any particular book using the number, and to return it to its proper place on the library shelves. The classification system is used in 200,000 libraries in at least 135 countries.

Early development (1873–1885)
Melvil Dewey (1851–1931) was an American librarian and self-declared reformer. He is best known for the Decimal System that he created, but he also was a founding member of the American Library Association and can be credited with the promotion of card systems in libraries and business. He developed the ideas for his library classification system in 1873 while working at Amherst College library. He applied the classification to the books in that library, until in 1876 he had a first version of the classification. In 1876, he published the classification in pamphlet form with the title A Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library. He used the pamphlet, published in more than one version during the year, to solicit comments from other librarians. It is not known who received copies or how many commented as only one copy with comments has survived, that of Ernest Cushing Richardson. His classification system was mentioned in an article in the first issue of the Library Journal and in an article by Dewey in the Department of Education publication "Public Libraries in America" in 1876. In March 1876, he applied for, and received copyright on the first edition of the index. The edition was 44 pages in length, with 2,000 index entries, and was printed in 200 copies.

Period of adoption (1885–1942)
The second edition of the Dewey Decimal system was published in 1885, with the title Decimal Classification and Relativ Index for arranging, cataloging, and indexing public and private libraries and for pamflets, clippings, notes, scrap books, index rerums, etc., and was 314 pages long, with 10,000 index entries. 500 copies were produced. Editions 3–14, published between 1888 and 1942, used a variant of this same title. Dewey modified and expanded his system considerably for the second edition. In an introduction to that edition Dewey states that "nearly 100 persons hav [sic] contributed criticisms and suggestions".

One of the innovations of the Dewey Decimal system was that of positioning books on the shelves in relation to other books on similar topics. When the system was first introduced, most libraries in the US used fixed positioning: each book was assigned a permanent shelf position based on the book's height and date of acquisition. Library stacks were generally closed to all but the most privileged patrons, so shelf browsing was not considered of importance. The use of the Dewey Decimal system increased during the early 20th century as librarians were convinced of the advantages of relative positioning and of open shelf access for patrons.

New editions were readied as supplies of previously published editions were exhausted, even though some editions provided little change from the previous, as they were primarily needed to fulfill demand. In the next decade, three editions followed closely on: the 3rd (1888), 4th (1891), and 5th (1894). Editions 6 through 11 were published from 1899 to 1922. The 6th edition was published in a record 7,600 copies, although subsequent editions were much lower. During this time, the size of the volume grew, and edition 12 swelled to 1243 pages, an increase of 25% over the previous edition.

In response to the needs of smaller libraries who were finding the expanded classification schedules difficult to use, in 1894, the first abridged edition of the Dewey Decimal system was produced. The abridged edition generally parallels the full edition, and has been developed for most full editions since that date. By popular request, in 1930, the Library of Congress began to print Dewey Classification numbers on nearly all of its cards, thus making the system immediately available to all libraries making use of the Library of Congress card sets.

Dewey's was not the only library classification available, although it was the most complete. Charles Ammi Cutter published the Expansive Classification in 1882, with initial encouragement from Melvil Dewey. Cutter's system was not adopted by many libraries, with one major exception: it was used as the basis for the Library of Congress Classification system.

In 1895, the International Institute of Bibliography, located in Belgium and led by Paul Otlet, contacted Dewey about the possibility of translating the classification into French, and using the classification system for bibliographies (as opposed to its use for books in libraries). This would have required some changes to the classification, which was under copyright. Dewey gave permission for the creation of a version intended for bibliographies, and also for its translation into French. Dewey did not agree, however, to allow the International Institute of Bibliography to later create an English version of the resulting classification, considering that a violation of their agreement, as well as a violation of Dewey's copyright. Shortly after Dewey's death in 1931, however, an agreement was reached between the committee overseeing the development of the Decimal Classification and the developers of the French Classification Decimal. The English version was published as the Universal Decimal Classification and is still in use today.

According to a study done in 1927, the Dewey system was used in the US in approximately 96% of responding public libraries and 89% of the college libraries. After the death of Melvil Dewey in 1931, administration of the classification was under the Decimal Classification Committee of the Lake Placid Club Education Foundation, and the editorial body was the Decimal Classification Editorial Policy Committee with participation of the American Library Association (ALA), Library of Congress, and Forest Press. By the 14th edition in 1942, the Dewey Decimal Classification index was over 1,900 pages in length and was published in two volumes.

Forging an identity (1942–present)
The growth of the classification to date had brought on significant criticism from medium and large libraries who were too large to use the abridged edition but found the full classification overwhelming. It had been Dewey's intention for the classification to be issued in three editions: the library edition, which would be the fullest edition; the bibliographic edition, in English and French, which was to be used for the organization of bibliographies rather than books on the shelf; and the abridged edition. In 1933, the bibliographic edition became the Universal Decimal Classification, which left the library and abridged versions as the formal Dewey Decimal Classification editions. The 15th edition, edited by Milton Ferguson, implemented the growing concept of the "standard edition," designed for the majority of general libraries but not attempting to satisfy the needs of the very largest or of special libraries. It also reduced the size of the Dewey system by over half, from 1,900 to 700 pages, a revision so radical that Ferguson was removed from the editorship for the next edition. The 16th and 17th editions, under the editorship of the Library of Congress, grew again to two volumes. However, by now, the Dewey Decimal system had established itself as a classification for general libraries, with the Library of Congress Classification having gained acceptance for large research libraries.

The first electronic version of Dewey was created in 1993. Although hard copy editions continue to be issued at intervals, the online WebDewey and Abridged WebDewey are updated quarterly.

Administration and publication
Administratively, the very early editions were managed by Dewey and a small editorial staff. Beginning in 1922, administrative affairs were managed by the Lake Placid Club Educational Foundation, a not-for-profit organization founded by Melvil Dewey. The ALA created a Special Advisory Committee on the Decimal Classification as part of the Cataloging and Classification division of ALA, in 1952. The previous Decimal Classification Committee was changed to the Decimal Classification Editorial Policy Committee, with participation of the ALA Division of Cataloging and Classification, and the Library of Congress.

Melvil Dewey edited the first three editions of the classification system and oversaw the revisions of all editions until his death in 1931. May Seymour became editor in 1891, until her death in 1921. She was followed by Dorcas Fellows, who was editor until her death in 1938. Constantin J. Mazney edited the 14th edition. Milton Ferguson was editor from 1949 to 1951. The 16th edition in 1958 was edited under an agreement between the Library of Congress and Forest Press, with David Haykin as director. Editions 16-19 were edited by Benjamin A. Custer and the editor of edition 20 was John P. Comaromi. Joan Mitchell was editor until 2013, covering editions 21-23. The current Editor-in-Chief is Michael Panzer of OCLC.

Copyright in editions 1-6 (1876–1919) was held by Dewey himself. Copyright in editions 7–10 were held by the publisher, The Library Bureau. On the death of May Seymour, Dewey conveyed the "copyryts and control of all editions" to the Lake Placid Club Educational Foundation, a non-profit chartered in 1922. The Online Computer Library Center (OCLC) of Dublin, Ohio, US, acquired the trademark and copyrights associated with the Dewey Decimal Classification system when it bought Forest Press in 1988. In 2003, the Dewey Decimal Classification came to national attention when OCLC sued the Library Hotel for trademark infringement for using the classification system as the hotel theme. The case was settled shortly thereafter.

Since 1988, the classification has been maintained by the OCLC, which also publishes new editions of the system. The editorial staff responsible for updates is based partly at the Library of Congress and partly at OCLC. Their work is reviewed by the Decimal Classification Editorial Policy Committee, a ten-member international board which meets twice each year. The four-volume unabridged edition is published approximately every six years, the most recent edition (DDC 23) in mid-2011. The web edition is updated on an ongoing basis, with changes announced each month. An experimental version of Dewey in RDF is available at dewey.info. This includes access to the top three levels of the classification system in 14 languages.

In addition to the full version, a single volume abridged edition designed for libraries with 20,000 titles or fewer has been made available since 1895. "Abridged 15" was published in early 2012.

Design
The Dewey Decimal Classification organizes library materials by discipline or field of study. Main divisions include philosophy, social sciences, science, technology, and history. The scheme is made up of ten classes, each divided into ten divisions, each having ten sections. The system's notation uses Arabic numbers, with three whole numbers making up the main classes and sub-classes and decimals creating further divisions. The classification structure is hierarchical and the notation follows the same hierarchy. Libraries not needing the full level of detail of the classification can trim right-most decimal digits from the class number to obtain a more general classification. For example:


 * 500 Natural sciences and mathematics
 * 510 Mathematics
 * 516 Geometry
 * 516.3 Analytic geometries
 * 516.37 Metric differential geometries
 * 516.375 Finsler Geometry

The classification was originally enumerative, meaning that it listed all of the classes explicitly in the schedules. Over time it added some aspects of a faceted classification scheme, allowing classifiers to construct a number by combining a class number for a topic with an entry from a separate table. Tables cover commonly used elements such as geographical and temporal aspects, language, and bibliographic forms. For example, a class number could be constructed using 330 for economics + .9 for geographic treatment + .04 for Europe to create the class 330.94 European economy. Or one could combine the class 973 for United States + .05 for periodical publications on the topic to arrive at the number 973.05 for periodicals concerning the United States generally. The classification also makes use of mnemonics in some areas, such that the number 5 represents the country Italy in classification numbers like 945 (history of Italy), 450 (Italian language), 195 (Italian philosophy). The combination of faceting and mnemonics makes the classification synthetic in nature, with meaning built into parts of the classification number.

The Dewey Decimal Classification has a number for all subjects, including fiction, although many libraries create a separate fiction section shelved by alphabetical order of the author's surname. Each assigned number consists of two parts: a class number (from the Dewey system) and a book number, which "prevents confusion of different books on the same subject." A common form of the book number is called a Cutter number, which represents the author and distinguishes the book from other books on the same topic.

Classes
(From DDC 23 )
 * 000 – General works, Computer science and Information
 * 100 – Philosophy and psychology
 * 200 – Religion
 * 300 – Social sciences
 * 400 – Language
 * 500 – Science
 * 600 – Technology
 * 700 – Arts & recreation
 * 800 – Literature
 * 900 – History & geography

Tables
(From DDC 23 )
 * T1 Standard Subdivisions
 * T2 Geographic Areas, Historical Periods, Biography
 * T3 Subdivisions for the Arts, for Individual Literatures, for Specific Literary Forms
 * T3A Subdivisions for Works by or about Individual Authors
 * T3B Subdivisions for Works by or about More than One Author
 * T3C Notation to Be Added Where Instructed in Table 3B, 700.4, 791.4, 808–809
 * T4 Subdivisions of Individual Languages and Language Families
 * T5 Ethnic and National Groups
 * T6 Languages

"Relativ Index"
The "Relativ Index" [sic] is an alphabetical index to the classification, for use both by classifiers but also by library users when seeking books by topic. The index was "relative" because the index entries pointed to the class numbers, not to the page numbers of the printed classification schedule. In this way, the Dewey Decimal Classification itself had the same relative positioning as the library shelf and could be used either as an entry point to the classification, by catalogers, or as an index to the Dewey-classed library itself.

Influence and criticism
Dewey Decimal Classification numbers formed the basis of the Universal Decimal Classification (UDC), which combines the basic Dewey numbers with selected punctuation marks (comma, colon, parentheses, etc.). Adaptations of the system for specific regions outside the English-speaking world include the Korean Decimal Classification, the New Classification Scheme for Chinese Libraries, and the Nippon Decimal Classification (Japanese).

Despite its widespread usage, the classification has been criticized for its complexity and limited scope of scheme-adjustment. In particular, the arrangement of subheadings has been described as archaic and as being biased towards an Anglo-American world view. In 2007–08, the Maricopa County Library District in Arizona, abandoned the DDC in favor of the Book Industry Standards and Communications (BISAC) system, one that is commonly used by commercial bookstores, in an effort to make their libraries more accessible for patrons. Several other libraries across the United States, and other countries (including Canada and The Netherlands) followed suit. The classification has also been criticized as being a proprietary system licensed by a single entity (OCLC), making it expensive to adopt.