Library classification
A library classification is a system of coding and organizing library materials (books, serials, audiovisual materials, computer files, maps, manuscripts, realia) according to their subject and allocating a call number to that information resource. Similar to classification systems used in biology, bibliographic classification systems group entities that are similar together typically arranged in a hierarchical tree structure (assuming none-faceted system).
Library classification forms part of the field of library and information science. It goes hand in hand with library (descriptive) cataloging under the rubric of cataloging and classification, sometimes grouped together as technical services. The library professional who engages in the process of cataloging and classifying library materials is called a cataloger or catalog librarian. Library classification systems are one of the two tools used to facilitate subject access. The other are alphabetical indexing languages such as Thesaurui and Subject Headings systems.
In the U.S., academic libraries generally use Library of Congress classification system and public and school libraries use Dewey Decimal Classification System.
Overview
Classification of a piece of work consists of two steps. Firstly the 'aboutness' of the material is ascertained. Next, a call number based on the classification system will be assigned to the work using the notation of the system.
It is important to note that unlike subject heading or Thesaurui where multiple terms can be assigned to the same work, in classification systems, each work can only be placed in one class. This is true also for faceted (see later) classification systems due to the enforcement of a citation order. Most classification systems like DDC and Library of Congress classification, also add a "cutter number" to each work which adds a code for the author of the work.
Classification systems in libraries generally play two roles. Firstly they facilitate subject access by allowing the user to find out what works or documents the library has on a certain subject. Secondly, they provide a known location for the information source to be located (e.g where it is shelved).
Until the 19th century, most libraries had closed stacks, so the library classification only served to organize the subject catalog. In the 20th century, libraries opened their stacks to the public and started to shelve the library material itself according to some library classification to simplify subject browsing.
Some classification systems are more suitable for aiding subject access, rather than for shelf location. For example, UDC which uses a complicated notation including plus, colons are more difficult to use for the purpose of shelf arrangement but are more expressive compared to DDC in terms of showing relationships between subjects. Similarly facteted classification schemes are more difficult to use for shelf arrangement, unless the user has knowledge of the citation order.
Depending on the size of the library collection, some libraries might use classification systems solely for one purpose or the other. In extreme cases a public library with a small collection might just use a classification system for location of resources but might not use a complicated subject classification system. Instead all resources might just be put into a couple of wide classes (Travel, Crime, Magazines etc). This is known as a "mark and park" classification method.
In the U.S., academic libraries generally use Library of Congress classification system and public and school libraries use Dewey Decimal Classification System.
Types
There are many standard systems of library classification in use, and many more have been proposed over the years. However in general, Classification systems can be divided into three types depending on how they are used.
- Universal schemes covering all subjects. Examples include Dewey Decimal Classification and Library of Congress Classification
- Specific classification schemes. Examples includes Iconclass, British classification of Music
- National schemes specially created for certain countries. Example is SAB.
In terms of functionality, classification systems are often described as
- enumerative: produce an alphabetical list of subject headings, assign numbers to each heading in alphabetical order
- hierarchical: divides subjects hierarchically, from most general to most specific
- faceted or analytico-synthetic: divides subjects into mutually exclusive orthogonal facets
There are few completely enumerative systems or faceted systems, most systems are a blend but favouring one type or the other. The most common classification systems, LCC and DDC, are essentially enumerative, though with some hierarchical and faceted elements (more so for DDC), especially at the broadest and most general level. The first true faceted system was the Colon classification of S. R. Ranganathan.
Specific classification systems used in English-speaking world
- Bliss bibliographic classification (BC)
- Dewey Decimal Classification (DDC)
- Library of Congress Classification (LC)
- Dickinson classification
(The above systems are the most common in the English-speaking world.)
- Harvard-Yenching Classification - An English classification system for Chinese language materials.
Specific classification systems in other languages
- Nippon Decimal Classification (NDC)
- Chinese Library Classification (CLC)
- Korean Decimal Classification (KDC)
Specific classification systems that rely on synthesis (faceted systems)
- Bliss bibliographic classification
- Colon classification
- Cutter Expansive Classification
- Universal Decimal Classification
- Brinkler classification
Newer classification systems tend to use the principle of synthesis (combining codes from different lists to represent the different attributes of a work) heavily, which is comparatively lacking in LC or DDC.
Comparing Classification Systems
As a result of differences in Notation, history, use of enumeration, hierarachy , facets, classification systems can differ in the following ways
- Type of Notation - Notation can be pure (consisting of only numerals for example) or mixed (consisting of both alphabets and numerals or other symbols).
- Expressiveness - This is the degree in which the notation can express relationship between concepts or structure.
- Whether they support mnemonics - For example the number 44 in DDC notation usually means it concerns some aspect of France. For example 598.0944 concerns "Birds in France". the 09 signifies country code, and 44 represents France.
- Hospitality - The degree in which the system is able to accommodates new subjects
- Brevity - Length of the notation to express the same concept
- Speed of updates and degree of support - The best classification systems are constantly being reviewed and improved.
- Consistency
- Simplicity
Library of Congress Classification System
The Library of Congress Classification (LCC) 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 — most public libraries and small academic libraries continue to use the Dewey Decimal Classification (DDC). It is not to be confused with the Library of Congress Subject Headings or Library of Congress Control Number.
The classification was originally developed by Herbert Putnam with the advice of Charles Ammi Cutter in 1897 before he assumed the librarianship of Congress. It was influenced by Cutter Expansive Classification, DDC, and was designed for the use by the Library of Congress. The new system replaced a fixed location system developed by Thomas Jefferson. By the time of Putnam's departure from his post in 1939 all the classes except K (Law) and parts of B (Philosophy and Religion) were well developed. It has been criticized as lacking a sound theoretical basis; many of the classification decisions were driven by the particular practical needs of that library, rather than considerations of epistemological elegance.
Although it divides subjects into broad categories, it is essentially enumerative in nature. It provides a guide to the books actually in the library, not a classification of the world.
The National Library of Medicine classification system (NLM) uses unused letters W and QS-QZ. Some libraries use NLM in conjunction with LCC, eschewing LCC's R (Medicine).
The system
| Letter | Subject area |
|---|---|
| A | General Works |
| B | Philosophy, Psychology, and Religion |
| C | Auxiliary Sciences of History |
| D | General and Old World History |
| E | History of America |
| F | History of the United States and British, Dutch, French, and Latin America |
| G | Geography, Anthropology, and Recreation |
| H | Social Sciences |
| J | Political Science |
| K | Law |
| L | Education |
| M | Music |
| N | Fine Arts |
| P | Language and Literature |
| Q | Science |
| R | Medicine |
| S | Agriculture |
| T | Technology |
| U | Military Science |
| V | Naval Science |
| Z | Bibliography, Library Science, and General Information Resources |
Dewey Decimal Classification System
The Dewey Decimal Classification (DDC, also called the Dewey Decimal System) is a proprietary system of library classification developed by Melvil Dewey in 1876, and has since then been greatly modified and expanded through twenty-two major revisions, the most recent in 2004.
How it works
The DDC attempts to organize all knowledge into ten main classes. The ten main classes are then further subdivided. Each main class has ten divisions, and each division has ten sections. Hence the system can be summarized in 10 main classes, 100 divisions and 1000 sections. DDC's advantage in choosing decimals for its categories allows it to be both purely numerical and infinitely hierarchical.
It also uses some aspects of a faceted classification 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 not less than three digits but otherwise of indeterminate length with a decimal point before the fourth digit, where present (e.g. 330 for economics + 9 for geographic treatment + 4 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; the whole number to the left of the decimal is in counting order, while the digits to the right of the decimal are compared one digit at a time, with a blank coming before zero. (Example: 050, 220, 330.973, 331 etc.) When two books have the same subject, and therefore the same classification number, the second line of the call number, which usually has the first letter or first several letters of the author's last name (or the title if there is no identifiable author), is placed in alphabetical order.
It is a common misconception that all books in the DDC are non-fiction. The DDC has a number for all books, including those that generally become their own section of fiction. If DDC rules are strictly followed, American fiction is classified in 813. Most libraries create a separate fiction section to allow shelving fiction in a more generalised fashion than Dewey provides for, or to avoid the space that would be taken up in the 800s.
DDC compared to other classification systems
DDC's numbers formed the basis of the more expressive but complex Universal Decimal Classification, which combines the basic Dewey numbers with selected punctuation marks (comma, colon, parentheses etc.). Besides its frequent revision, DDC's main advantage over its chief rival—the Library of Congress Classification 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 for most users.
DDC and UDC are also more flexible than Library of Congress Classification because of greater use of facets (via auxiliary tables) while Library of Congress Classification is almost totally enumerative.
On the flip side, 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. Another side effect of this is that DDC notations can be very much longer compared to the equivalent class in other classification systems.
Another disadvantage of DDC is that it was developed in the 19th century, by essentially one man, and was built on a top down approach to classify all human knowledge which made it difficult to adapt to changing fields of knowledge. In contrast, 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 for covering those areas. 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.
The Library of Congress Classification system is not without problems; because each area is developed by an expert according to demands of cataloging, there is little consistency. It is also highly US-centric (more so than DDC) because of the nature of the system, and compared to DDC and UDC it has been translated into far fewer languages.
Ownership and administration
The Online Computer Library Center of Dublin, Ohio, acquired the trademark and any copyrights associated with the Dewey Decimal System when it bought Forest Press in 1988. OCLC maintains the classification system and publishes new editions of the system. 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 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.
Classes
The system is made up of ten main classes or categories, each divided into ten secondary classes or subcategories, each having ten subdivisions of its own. For a more detailed list, see List of Dewey Decimal classes.
- 000 – Computer science, information, and general works
- 100 – Philosophy and psychology
- 200 – Religion
- 300 – Social sciences
- 400 – Language
- 500 – Science
- 600 – Technology
- 700 – Arts and recreation
- 800 – Literature
- 900 – History and geography
See also
ReferencesISBN links support NWE through referral fees
External links
- An annotated bibliography on Library Classification and Subject Approaches to Information - by Salman Haider, Librarian (Cataloging), US Library of Congress, New Delhi Overseas Office
- Library of Congress Cataloging home page
- Classification outline
- How to read LCC call numbers
- Complete list of Dewey Decimal Classes
- OCLC's Dewey Decimal website
- Full text of A Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library (Dewey Decimal Classification) (1876) from Project Gutenberg
- "What's so great about the Dewey Decimal System?" at Straight Dope, 31 January 2006
- A History of the D.D.C. System and its Creator Melville Dewey by University of British Columbia's mission, the School of Library, Archival and Information Studies
- A Dewey Decimal System Tutorial by the Illinois State Library, funded by the Gates Foundation
- An annotated bibliography on Library Classification and Subject Approaches to Information by Salman Haider, Librarian (Cataloging), US Library of Congress, New Delhi Overseas Office
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