SUBJECT CLASSIFICATION & CALL NUMBERS

What are Call Numbers?

Materials in a library are shelved in "call number" order.  The call number for a book is usually located on the "spine" or end panel of the book, but may be located on the front cover of thinner books.  There are two types of call numbers commonly used in libraries in the United States, Dewey Decimal and Library of Congress.  Most academic libraries, including PCC, use Library of Congress (LC) call numbers.  

Call numbers can be thought of as an alpha-numeric decimal filing system.  Numbers to the left hand side of the decimal point are read as whole numbers while numbers to the right hand side of the decimal point are read as individual digits of ten.  The publication year, volume or part number, or copy number is frequently placed at the end of an LC call number.  

HM701. D47 1997 v.1 c.2

What are the cards on the end of the shelves for?

These are guide cards to help you find books on the shelves.  They show the range of books on one side of a shelf in the library using the first part of the call number for the first and last book on that side of the shelf.  All one needs to do is place the call number of the book they are looking for within the range on one of the cards and you've narrowed down the search for your book to one side of one shelf.  Then, simply focus your search on the entire call number to find your book.

What is the relationship between call numbers and subject classifications?

Students have a general misunderstanding about how books and other materials are arranged in a library. They comprehend that there is some order, but don't understand the relationship between the organization of knowledge using classification systems and call numbers.  Like the organizational system used by science to logically organize or classify the animal and plant kingdoms, known as taxonomy, subject classification systems organization knowledge into hierarchies stemming from the general to increasingly specific treatment of a subject.  For example, in the LC call number noted above H is the general class for the Social Sciences.  HM is the class for the Social Science discipline of Sociology.  HM701 is the LC class for the sociological study of social systems.  

In a large scale organization of knowledge, such as a library, classification systems organize knowledge to further human understanding of what is known and for logical retrieval of desired information.  In the Library of Congress system, the first part of an LC call number is a code indicating the subject matter of a book.  Thus, books on the same or related subjects are shelved adjacent or in close proximity to one another in a library.  Review the Web pages linked below to learn more about the relationship between call numbers, classification systems, and the organization of knowledge.

Introduction to the Library of Congress Subject Classification System

The Complete LC Subject Classification System Breakdown

Matt Rosenberg's "Understanding Call Numbers" (2 Page Print-out)

Lake Sumter's LC Page