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Library Organization and Classification Systems

Library Classification Systems

University of Illinois Libraries use several different classification systems to designate materials in their collections. The most common designation is the Dewey Decimal system, followed by the Library of Congress system.



Dewey Decimal Classification

This classification scheme, designed by Melville Dewey in 1876, is used by most of the libraries on campus. Dewey divides knowledge into ten main classes with further subdivisions accompanied by decimal notation. This notation repeats patterns, develops subjects with parallel construction, and repeats standard subdivisions so that it is easy to browse the shelves in a logical manner. Learn how to read Dewey Call Numbers.

Library of Congress Classification

A classification system developed and used at the Library of Congress since 1897, the Library of Congress Classification system (LC) divides the field of knowledge into twenty large classes with an additional class on general works. This notation allows more combinations and greater specificity without long notations. The Law Library, Music Library and Asian Library use LC classification schemes for all or part of their collections. Learn how to read LC Call Numbers.

Most of the libraries at the University of Illinois at Urbana-Champaign use the Dewey call number system; you are probably familiar with these call numbers from their widespread use in public libraries. A few University of Illinois libraries, however - e.g., Asian, Law, and Music - use another system for organizing materials called the Library of Congress (LC) system.

The LC system originated in the  Library of Congress, a private library for senators and representatives in Washington, as a way of organizing materials on shelves. In recent decades, as LC has made its records available electronically, more libraries have adopted LC for both shelving and cataloging. Once an item is LC cataloged, you will need to understand the number to retrieve the physical item you have selected.

What Do the Parts of the Call Number Mean and How are Call Numbers Arranged on the Shelves?

  • Like Dewey, LC generally organizes materials by subject.
  • The LC number appears in  three main parts, and may contain  additional parts that  together provide a unique identifier for the item. 
  • One or more parts may be omitted; this represents the judgment of the cataloger that the remaining parts  suffice to provide a unique identifier.
  • The  three main parts are organized in this way:
  1. letter or letters (KF 801 .C65) 
    A single letter represents a broad, general subject 
    For Example: K = Law; 
    multiple letters mean a narrower subject within it 
    For Example: KF = US federal law. 
    This part of the call number is arranged alphabetically on the shelves, so J would come before K which would come before KF
  2. number (KF  801 .C65) 
    This middle part further defines the subject. 
    For Example: In the subject area of law, it designates a type of material. 801 = general/comprehensive works. 
    To determine the arrangement of the call number on the shelves, read these numbers the way you would count: 30 comes before 300 which
      comes before 3000.
  3. one or more  Cutter numbers (KF 801  .C65
    Named after a cataloguer, this number represents the beginning letter of a person's (author, editor, etc.) last name with a number that interpolates it between other names beginning with the same letter 
    For  Example: 
    Calamari, John D. = .C26 
    Corbin, Arthur L. = .C65 

    The above number may be preceded by a cutter number that further divides the subject, or gives some information about the form of the item, such as whether it is an outline, form book, or case book. 
    To determine the arrangement on the shelves, read Cutter numbers the way you would read a decimal: .3 comes before .301 which comes before .31.
  • The LC number may have  additional parts:
  1. date: (KF 801 .C65  1960) which distinguishes among different editions of the same work;
  2. volume number (KF 801 .C65  v.3A1960).

LC Classification Scheme

The Library of Congress Classification Scheme allows for greater precision in most fields and more room for expansion than the Dewey Decimal Classification System.

Each Library of Congress classification is represented by a set of capital letters and numbers. The first letter in the set indicates one of 21 major areas of knowledge.

A -- General Works 
B -- Philosophy, psychology, and religion 
C -- History: Auxiliary Sciences 
D -- History: General and Old World 
E -- History: America and U.S., general 
F -- History: America and U.S., local 
G -- Geography, anthropology, folklore, etc. 
H -- Social sciences, economics, business, sociology 
J -- Political Sciences 
K -- Law 
L -- Education 
M -- Music 
N -- Fine arts 
P -- Philology, linguistics, language, and literature 
Q -- Science 
R -- Medicine 
S -- Agriculture 
T -- Technology 
U -- Military Science 
V -- Naval science 
Z -- Bibliography and library science 
I, O, X, and Y are not used

Additional information about the Library of Congress appears on its Web FAQ page at:  http://lcweb.loc.gov/faq/

Superintendent of Documents Classification 

The U.S. Superintendent of Documents developed this system (also called SuDocs) for the arrangement of federal government publications. Arrangement is basically by issuing agency. The Documents Library uses this classification system.

The Superintendent of Documents (SuDocs) classification system for publications generally groups together documents by issuing agency. SuDocs numbers consist of a letter, designating the particular issuing agency, followed by numbers identifying subordinate bureaus within the agencies and specific publications. Below is a list of prefixes and their corresponding agencies:

  • A: Agriculture Department
  • C: Commerce Department
  • C3: Census Bureau (Commerce Dept.)
  • D: Defense Department
  • E: Energy Department
  • ED: Education Department
  • GA: General Accounting Office
  • HE: Health and Human Services Department
  • I: Interior Department
  • I19: U.S.Geological Survey (Interior Department)
  • J/Ju: Justice and Judiciary
  • L: Labor Department
  • LC: Library of Congress
  • NAS: National Aeronautics and Space Administration
  • S: State Department
  • T: Treasury Department
  • X,Y: Congress

United Nations Documents Classification

United Nations classification numbers--known as "symbols"--are composed of letters and numerals separated by slashes. A symbol is printed on the cover of a document--usually in the upper right-hand corner--and is made up of three to five segments:

  1. The first segment--and sometimes the second as well--identifies the document's issuing body. Ordinarily, the first segments of documents issued by the U.N.'s main bodies consisted of the following:

    • Symbol: Issuing Body
    • A/: General Assembly
    • E/: Economic and Social Council
    • S/: Security Council
    • ST/: Secretariat
    • T/: Trusteeship Council

    The most common segments for subsidiary bodies include the following.

    • Symbol: Subsidiary Body
    • AC.: Ad hoc committee
    • E C.: Standing or permanent committee
    • CN.: Commission
    • CONF.: Conference
    • GC.: Governing Council
    • PC.: Preparatory Committee
    • SC.: Subcommittee
    • Sub.: Subcommission
    • WG.: Working group
    • WP.: Working party


    Example: A/ in the symbol A/50/PV.45 indicates that the document was issued by the General Assembly. 
    Example: In the symbol A/C.5/49/25, the first two segments-A/C.5/--indicate that the document was produced by the General Assembly's Fifth Committee.

    Occasionally, the second segment indicates not the issuing subbody but rather the type of document, as in the case of resolutions. Documents that follow the format S/RES/[number] are Security Council resolutions, and those that follow the format A/RES/[session]/[number] are General Assembly resolutions.

  2. The segment following the issuing body usually indicates the session or year in which the document was published. 

    Example: The symbol A/C.5/49/25 was assigned to a document produced during the General Assembly's 49th session. 
    Example:The symbol E/1996/28 was assigned to a document issued in 1996.

  3. The number following the session or year is the individual document number. 

    Example: A/C.5/49/25 is the classification number for the 25th document produced by its issuing body in the 49th session.

  4. Some symbols also include an acronym or abbreviation-placed in the middle or at the end-- denoting a document type or distribution classification or indicating that the original text has been modified. 

    Example: In E/CN.4/1996/NGO/75, "NGO/" indicates that the document was produced by a nongovernmental organization.

    Other acronyms and abbreviations include the following:

    • Add.: Addendum (an addition of text to the main document)
    • Amend.: Amendment
    • Corr.: Corrigendum (a modification of a document)
    • CRP.: Conference room paper
    • Excerpt: Excerpt
    • INF.: Information series
    • L.: Limited distribution
    • MIN.: Minutes
    • NGO/: Non-governmental organization
    • PET/: Petition
    • PV.: Verbatim record of a meeting
    • R.: Restricted distribution
    • RES/: Resolution
    • Rev.: Revision
    • RT/: Record of testimony
    • SR.: Summary record
    • WP: Working paper

    The symbols for certain subsidiary bodies begin with the subbody's acronym, omitting the letter that identifies the parent body. Symbols for the Committee on the Elimination of Discrimination Against Women (CEDAW) are a case in point. Even though the committee is part of the General Assembly, symbols for CEDAW always begin with CEDAW/ rather than A/CEDAW/. The table below lists some of the U.N. subbodies to which this practice applies.

    • Symbol: Subsidiary Body
    • AT/: Administrative Tribunal
    • CAT/C/: Committee Against Torture
    • CCPR/C/: Human Rights Committee
    • CEDAW/C/: Committee on the Elimination of Discrimination Against Women
    • CERD/C/: Committee on the Elimination of Racial Discrimination
    • CRC/C/: Committee on the Rights of the Childd
    • DP/: United Nations Development Programme
    • DPI/: Dept. of Public Information
    • ECE/: Economic Commission for Europe
    • ID/: United Nations Industrial Development Organization*
    • LC/: Economic Commission for Latin America and the Caribbean
    • UNCTAD/: United Nations Conference on Trade and Development
    • UNEP/: United Nations Environment Programme
    • UNIDIR/: United Nations Institute for Disarmament Research
    • UNIDO/: United Nations Industrial Development Organization*

    *These prefixes were used for UNIDO documents when the organization was a division within the United Nations. UNIDO became an independent, Specialized Agency in 1985.

    Learn to read a UN Call Number

    The United Nations Collection on Deck 5 East of the Main Stacks includes both catalogued and uncatalogued materials in paper format.

    All U.N. documents on Deck 5 East and in the U.N. reference collection (located in room 200 of the Main Library) are arranged by symbol. An initial letter(s) in upper case followed immediately by a slash (e.g., A/ or TD/) distinguishes a document's symbol from other numbers that may appear on the piece.

    The following rules will allow you to determine the proper shelving sequence of any item:

    • Segments beginning with letters should be compared letter by letter and arranged alphabetically. A document bearing the symbol A/CN.1/1 would be shelved before a document having the symbol A/CONF.1/1, since "CN" precedes "CONF" when both abbreviations are placed in alphabetic order.
    • All numbers (including years) are treated as whole numbers and never as decimals. The symbol A/50/PV.10 would be found immediately after A/50/PV.9 on the shelf, since the number 10 is greater than 9.
    • Segments beginning with numbers come before segments beginning with letters. A/50/2 is shelved before A/50/PV.1 since 2 is a numeral and the corresponding segment of A/50/PV.1 begins with the letter "P."
    • The call number for a   cataloged U.N. document consists of the prefix "UN." followed by the document's symbol. The call number for a piece having the symbol A/50/238 would appear as follows:  
      UN. A/50/ 238
    • Cataloged documents in the U.N. Collection are interfiled with uncataloged documents. A cataloged document with the call number UN.A/50/238 would be shelved between the documents bearing the symbols A/50/237 and A/50/239.