Subject Headings & Classification Systems

Sections:
1) Types of Print Resources
2) Subject Headings & Classification Systems
3) Call Numbers
4) Author, Title, Subject & Keyword Searching

THE ORGANIZATION OF LIBRARY MATERIALS
Imagine that you're a bookworm, constantly buying and reading new books. At first, your book collection is small enough that you simply add your new purchases randomly to your bookshelf in no particular order. But by the time it grows to 100 or more books, you decide to organize your collection so that you can find what you need easily without a lot of wasted time and effort. You could arrange your books by author, title, color, size, date purchased, language, hardback vs. paperback, or several other categories. Any of these approaches is perfectly valid for an individual with a relatively small collection, but libraries use none of these approaches. How do libraries - which contain thousands and in some cases millions of books - arrange their collections?

Libraries organize their collections according to subject matter. This is an enormously complex, on-going project that is based on three organizational tools: subject headings, classification systems, and call numbers. Call numbers will be discussed in the next section.

SUBJECT HEADINGS
When a book or other item is added to a library's collection, a specialist known as a cataloger examines it and decides what that book is about. The cataloger must describe the subject content of that book as completely as possible by using standardized, officially approved words or groups of words known as subject headings. He/she will assign between 1 and 5 subject headings to describe the content of a book. Subject headings assigned by a human cataloger, therefore, make it possible for you to do a subject search.

Subject headings can be one word, two or more words, a phrase, a city, a country, a geographic region, or a person. For example, the following are all valid subject headings:

HOSPITALS
ELECTROCHEMISTRY
WOMEN IN MOTION PICTURES
DATABASE MANAGEMENT
FRANCE ECONOMETRICS
DATABASE MANAGEMENT
HEMINGWAY, ERNEST

Sometimes, the first word or phrase that comes to your mind is, in fact, the "correct" (i.e., the valid) subject heading. For example, books on CHILDREN'S LITERATURE or PHOTOGRAPHY may be found under those subject words.

At other times, however, subject headings are expressed in less obvious terms. For example, you may look up the subject MOVIES in a catalog or index and find nothing. Then you try FILMS --again, no luck. You might assume that there is no information on the subject, but there are in fact many books and articles on movies under the subject heading MOTION PICTURES.

Listed below are more examples of topics with subject headings that wouldn't immediately come to mind:

Topic: Finding a job
Subject Heading: APPLICATIONS FOR POSITIONS

Topic: The American Revolution
Subject Heading: UNITED STATES -- HISTORY -- REVOLUTION

Topic: Medieval art
Subject Heading: ART -- MEDIEVAL

Topic: Date rape
Subject Heading: ACQUAINTANCE RAPE

Topic: Sleeping sickness
Subject Heading: AFRICAN TRYPANOSOMIASIS

Topic: Southeast Asia
Subject Heading: ASIA -- SOUTHEASTERN

As you can see, subject headings often use very formal language. Given below are some other characteristic features of subject headings:

* Subject headings are usually given in plural form. Thus, SHARKS is used rather than SHARK and APARTMENT HOUSES, not APARTMENT HOUSE.

* In general, slang, jargon, and highly specialized terminology are avoided in subject headings in favor of standard English. For example, drunkenness will not be found under terms such as "smashed," "bombed," or "wasted." Valid headings for drunkenness include ALCOHOL ABUSE, ALCOHOL DRINKING, and SUBSTANCE ABUSE.

* Subject headings are sometimes inverted to emphasize the most important word. In such cases, you can determine the correct subject heading by simply reversing the words you're likely to think of first. For example, the subject heading for information on abstract art is ART, ABSTRACT. For American authors, the heading is AUTHORS, AMERICAN.

SUBDIVISIONS - ADDING PRECISION TO A SUBJECT HEADING
Since subject headings often cover somewhat broad concepts, additional words called subdivisions (sometimes called subheadings) are often added as a way to focus on a more specific aspect of the subject. Subdivisions are separated from the main heading by a dash (--) and identify various aspects of a subject that may be of interest to you. For example, AIRPLANES is a valid, but very broad, subject heading. Many subdivisions, however, can be found which focus on specific aspects of airplanes. Listed below are only a few of the many subdivisions under the main heading AIRPLANES:

AIRPLANES -- BRAKES
AIRPLANES -- DESIGN AND CONSTRUCTION
AIRPLANES -- FUEL CONSUMPTION
AIRPLANES -- INSPECTION
AIRPLANES -- SPEED
AIRPLANES -- WINGS
Subdivisions can be one of four types:

* Topical subdivisions narrow the subject to a particular aspect. The subdivisions in the above example on AIRPLANES are all topical subdivisions. Other examples of main headings followed by topical subdivisions include:

CORN -- HARVESTING
WOMEN -- EMPLOYMENT
MASS MEDIA -- SOCIAL ASPECTS
* Geographical subdivisions narrow the subject to a particular geographic area, such as a country, state or city. For example:

MASS MEDIA -- UNITED STATES
* Form subdivisions specify a particular type or form of publication. They tell you about a book's publication format rather than its subject. For example:

MASS MEDIA -- DICTIONARIES
MASS MEDIA -- HANDBOOKS, MANUALS, ETC.
* Chronological subdivisions narrow the subject to a specific date or time period. They are commonly seen when dealing with historical subjects. For example, when searching for information on any aspect of American history, always start with UNITED STATES -- HISTORY and then add a chronological subdivision such as:

UNITED STATES -- HISTORY -- 19TH CENTURY
UNITED STATES -- HISTORY -- 1865-1877

LIBRARY OF CONGRESS SUBJECT HEADINGS (LCSH) : A CONTROLLED VOCABULARY
Now that you know a little bit about subject headings, you may wonder where they come from. Who decides on the exact word(s) and subdivisions that become an officially approved subject heading? These decisions are made by specialists, known as catalogers, who work for the largest library in the world: the Library of Congress in Washington, D.C. Almost every library in the United States uses the subject headings decided upon by catalogers at the Library of Congress.

In order to be consistent in their work, catalogers assign subject headings chosen from a standardized, official list. This list of approved subject terms is known as a controlled vocabulary. The controlled vocabulary used by catalogers at the Library of Congress is known as the Library of Congress Subject Headings or simply LSCH.

Why should a controlled vocabulary system matter to you, the researcher? Simply stated, if you pay attention to subject headings, you can take advantage of the order and precision it attempts to bring to the database. Although the formal language used in subject headings can sometimes lead to problems when doing subject searching -- i.e., you may not be able to "guess" the correct term(s) -- you should at least be aware of the existence and purpose of controlled vocabularies.

CLASSIFICATION SYSTEMS
As you know, libraries organize their collections according to subject matter. This arrangement is intended to be convenient for library users since books on the same subject are placed together on the same shelf. But in order for subject-based organization to accomplish its goals, it must be based on a definite and established plan that can be referred to again and again. Therefore, libraries have created classification systems. A classification system is an established plan that divides all knowledge into precise categories and subcategories. Each category is called a "class" and each subcategory is called a "division" or "subdivision." This division of knowledge always proceeds from general classes to more and more specific subdivisions.

Although most public libraries use the Dewey system, most college and university libraries (including CSM) use a different classification system: the Library of Congress classification system. Devised in 1897, the Library of Congress system (or LC system) is a comprehensive, highly detailed, subject-based organization system that uses combinations of letters and numbers to represent subject areas.

THE LIBRARY OF CONGRESS CLASSIFICATION SYSTEM
It divides all knowledge into 21 main classes indicated by a single letter of the alphabet :

A General Works
B Philosophy, Psychology, Religion
C History: Auxiliary science
D History: General and Old World
E-F History: America
G Geography
H Social Sciences
J Political Sciences
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 and Library Science

There is one final point to make about classification systems. Theoretically, a classification system should work in such a way that books on any one subject would be found in only one place. However, this becomes impossible for those books that deal with more than one subject. For example, a book such as Women, Philosophy, and Sport: A Collection of Critical Essays (Scarecrow Press 1983) could be classified under women's studies (HQ), philosophy (B), or sports (GV), which are far apart from each other on the shelves (Mann 50). However, only one class number can be assigned to this book and the cataloger will have to decide by examining the book and choosing the class number that corresponds to the subject covered most prominently by that book. Subjects covered in the book but not reflected in the call number chosen by the cataloger will be described by additional subject headings assigned by the cataloger.