Dewey Decimal Classification
Encyclopedia
Dewey Decimal Classification, (also called the Dewey Decimal System) is a proprietary system of library classification
Library classification
A library classification is a system of coding and organizing documents or library materials according to their subject and allocating a call number to that information resource...

 developed by Melvil Dewey
Melvil Dewey
Melville Louis Kossuth Dewey was an American librarian and educator, inventor of the Dewey Decimal system of library classification, and a founder of the Lake Placid Club....

 in 1876.

It has been greatly modified and expanded through 23 major revisions, the most recent in 2011. This system organizes books on library shelves in a specific and repeatable order that makes it easy to find any book and return it to its proper place. The system is used in 200,000 libraries in at least 135 countries.

A designation such as Dewey 16 refers to the 16th edition of the DDC.

Design

The DDC attempts to organize all knowledge into ten main classes. The ten main classes are each further subdivided into ten divisions, and each division into ten sections, giving ten main classes, 100 divisions and 1000 sections. DDC's advantage in using decimal
Decimal
The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations....

s for its categories allows it to be purely numerical, while the drawback is that the codes are much longer and more difficult to remember as compared to an alphanumeric system. Just as an alphanumeric system, it is infinitely hierarchical. It also uses some aspects of a faceted classification
Faceted classification
A faceted classification system allows the assignment of multiple classifications to an object, enabling the classifications to be ordered in multiple ways, rather than in a single, predetermined, taxonomic order. A facet comprises "clearly defined, mutually exclusive, and collectively exhaustive...

 scheme, combining elements from different parts of the structure to construct a number representing the subject content (often combining two subject elements with linking numbers and geographical and temporal elements) and form of an item rather than drawing upon a list containing each class and its meaning.

Except for general works and fiction, works are classified principally by subject, with extensions for subject relationships, place, time or type of material, producing classification numbers of at least three digits but otherwise of indeterminate length with a decimal point before the fourth digit, where present (for example, 330 for economics + .9 for geographic treatment + .04 for Europe = 330.94 European economy; 973 for United States + .05 form division for periodicals = 973.05 periodicals concerning the United States generally).

Books are placed on the shelf in increasing numerical order of the decimal number, for example, 050, 220, 330, 330.973, 331. When two books have the same classification number the second line of the call number (usually the first letter or letters of the author's last name, the title if there is no identifiable author) is placed in alphabetical order.

The DDC has a number for all books, including fiction: American fiction is classified in 813. Most libraries create a separate fiction section to allow shelving in a more generalized fashion than Dewey provides for, or to avoid the space that would be taken up in the 800s, or simply to allow readers to find preferred authors by alphabetical order of surname.

Some parts of the classification offer options to accommodate different kinds of libraries. An important feature of the scheme is the ability to assign multiple class numbers to a bibliographical item and only use one of them for shelving. The added numbers appear in the classified subject catalog (though this is not the usual practice in North America). For the full benefit of the scheme the relative index and the tables that form part of every edition must be understood and consulted when required. The structure of the schedules is such that subjects close to each other in a dictionary catalog are dispersed in the Dewey schedules (for example, architecture of Chicago quite separate from geography of Chicago).

Classes listed

The system is made up of seven tables and ten main classes, each of which is divided into ten secondary classes or subcategories, each of which contain ten subdivisions.

The tables are:
  • standard subdivision
  • areas
  • subdivision of individual literatures
  • subdivisions of individual languages
  • racial, ethnic, national groups
  • languages
  • persons


The classes are:
  • 000 – Computer science, information and general works
  • 100 – Philosophy and psychology
  • 200 – Religion
  • 300 – Social sciences
  • 400 – Language
  • 500 – Science (including mathematics)
  • 600 – Technology and applied Science
  • 700 – Arts and recreation
  • 800 – Literature
  • 900 – History and geography

Administration and publication

While he lived, Melvil Dewey edited each edition himself: he was followed by other editors who had been very much influenced by him. The earlier editions were printed in the peculiar spelling that Dewey had devised: the number of volumes in each edition increased to two, then three and now four.

The Online Computer Library Center of Dublin
Dublin, Ohio
Dublin is a city in Franklin, Delaware, and Union counties in the U.S. state of Ohio. The population was 41,751 at the 2010 census. Dublin is a suburb of Columbus, Ohio. Approximately 57,000 people live within the Dublin school district....

, Ohio, United States, acquired the trademark and copyrights associated with the DDC when it bought Forest Press in 1988. OCLC maintains the classification system and publishes new editions of the system. The editorial staff responsible for updates is based partly at the Library of Congress
Library of Congress
The Library of Congress is the research library of the United States Congress, de facto national library of the United States, and the oldest federal cultural institution in the United States. Located in three buildings in Washington, D.C., it is the largest library in the world by shelf space and...

 and partly at OCLC. Their work is reviewed by the Decimal Classification Editorial Policy Committee (EPC), which is a ten-member international board that 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.

The work of assigning a DDC number to each newly published book is performed by a division of the Library of Congress, whose recommended assignments are either accepted or rejected by the OCLC after review by an advisory board; to date all have been accepted.

In September 2003, the OCLC sued the Library Hotel
Library Hotel
The Library Hotel is a 60-room boutique hotel in New York City, located at 299 Madison Avenue , near the New York Public Library, Bryant Park, and Grand Central Terminal. The Hotel was designed by architect Stephen B...

 for trademark infringement. The settlement was that the OCLC would allow the Library Hotel to use the system in its hotel and marketing. In exchange, the Hotel would acknowledge the Center's ownership of the trademark and make a donation to a nonprofit organization promoting reading and literacy among children.

Influence

DDC's numbers formed the basis of the more expressive but complex Universal Decimal Classification
Universal Decimal Classification
The Universal Decimal Classification is a system of library classification developed by the Belgian bibliographers Paul Otlet and Henri La Fontaine at the end of the 19th century. It is based on the Dewey Decimal Classification, but uses auxiliary signs to indicate various special aspects of a...

 (UDC), which combines the basic Dewey numbers with selected punctuation marks (comma, colon, parentheses, etc.). Adaptations of DDC for specific regions outside the English-speaking world include the Korean Decimal Classification
Korean Decimal Classification
The Korean Decimal Classification is a system of library classification used in Korea. The main classes are the same as in the Dewey Decimal Classification but these are in a different order: Natural sciences 400; Technology and engineering 500; Arts 600; Language 700.-Main classes:* 000 General*...

, the New Classification Scheme for Chinese Libraries
New Classification Scheme for Chinese Libraries
The New Classification Scheme for Chinese Libraries is a system of library classification developed by Yung-Hsiang Lai since 1956. It is modified from "A System of Book Classification for Chinese Libraries" of Liu Guojun, which is based on the Dewey Decimal System.The scheme is developed for...

 and the Nippon Decimal Classification
Nippon Decimal Classification
The Nippon Decimal Classification is a system of library classification developed for mainly Chinese and Japanese language books maintained by the Japan Library Association since 1956. It is based on the Dewey Decimal System...

 (Japanese).

Comparison with Library of Congress Classification

Besides its frequent revision, DDC's main advantage over its chief American rival, the Library of Congress Classification
Library of Congress Classification
The Library of Congress Classification is a system of library classification developed by the Library of Congress. It is used by most research and academic libraries in the U.S. and several other countries; for example, Australia and Taiwan, R.O.C. It is not to be confused with the Library of...

 system developed shortly afterward, is its simplicity. Thanks to the use of pure notation, a mnemonics system and a hierarchical decimal place system, it is generally easier to use.

DDC and UDC are more flexible than Library of Congress Classification because of greater use of facets (via auxiliary tables) while Library of Congress Classification
Library of Congress Classification
The Library of Congress Classification is a system of library classification developed by the Library of Congress. It is used by most research and academic libraries in the U.S. and several other countries; for example, Australia and Taiwan, R.O.C. It is not to be confused with the Library of...

 is almost totally enumerative.

DDC's decimal system means that it is less hospitable to the addition of new subjects, as opposed to Library of Congress Classification, which has 21 classes at the top level. DDC notations can be much longer compared to other classification systems.

Another disadvantage of DDC is that it was developed in the 19th century essentially by one man and was built on a top-down approach to classify all human knowledge, which makes it difficult to adapt to changing fields of knowledge. The Library of Congress Classification system was developed based mainly on the idea of literary warrant; classes were added (by individual experts in each area) only when needed for works owned by the Library of Congress. As a result, while the Library of Congress Classification system was able to incorporate changes and additions of new branches of knowledge, particularly in the fields of engineering and computer science (the greater hospitability of the Library of Congress Classification was also a factor), DDC has been criticized for being inadequate in covering those areas. It is asserted that, as a result, most major academic libraries in the US do not use the DDC because the classification of works in those areas is not specific enough, although there are other reasons that may truly be more weighty, such as the much lower expense of using a unique "pre-packaged" catalog number instead of having highly skilled staff members engaging in the time-consuming development of catalog numbers.

The Library of Congress Classification system is not without problems. For example, it is highly US-centric because of the nature of the system, and it has been translated into far fewer languages than DDC and UDC.

External links

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