Sunday, November 22, 2009

The call number

The purpose of a call number is to establish the exact location where a library item is shelved and can be retrieved, and to establish a logical order for its location within the library.

There are two parts to a call number: the classification number and the cutter. The classification number represents the first subject area, while the subsequent cutter or cutters represent either subtopics within this classification or, if it is the final cutter, the main entry of the item, i.e. the title or author. In the case of books and monographs, the final cutter also includes the year in which it was published.

There are two main library classification systems employed in the U.S. -- the Library of Congress system, used in most university libraries, and the Dewey Decimal system, used in most public libraries, and in libraries outside the U.S. The difference in appearance is that the LC classification system is alpha numeric, while the Dewey classification system is numeric.

At this point I will talk only about the LC system as that is what I work with daily, but for more information on the Dewey classification system click here for a listing of Dewey classification numbers, and here for a brief history and description.

The LC classification, as mentioned, is alpha numeric. Usually there is either one or two letters, followed by numbers; in the K series for law, it is often three letters, the three letters representing the country. Here is an example of an LC call number, for the book, Ho Chi Minh, by William J. Duiker, published in 2000:

DS560.72.H6 D85 2000

DS560.72 is for biography of North Vietnamese political leaders, H6 is for Ho Chi Minh, D85 is for William Duiker, and 2000 is for the year in which this edition was published. DS560.72 is the classification part of the call number, while H6 and D85 are the two cutters. Note that under this classification, all books whose primary subject heading is biography of Ho Chi Minh would be shelved in one section and within that the books would be arranged alphabetically by author, and for the same author the books would be listed chronologically, usually reflecting a newer edition.

Classification numbers are determined by the subject headings, with some exceptions, most notably literary works, where the classification is first based on country and then by author. For example:

PL4378.9.V86 S6213 2002

This is the call number for the book, Dumb Luck by Vũ Trọng Phụng, originally published in Vietnamese as Śô đỏ. PL4378.9 is for individual works of Vietnamese authors, V86 is the cutter for Vũ Trọng Phụng, and S6213 is the cutter for the original title, Śô đỏ, with the number 62 for the title, and the number 13 representing the fact that it is an English translation.

I will discuss this more later but in the next entry I will talk about searching for books in OCLC.


  1. Have you ever worked with Universal Decimal Classification? I know it's based on DDC, but it varies on some points.

  2. No,I have not. I guess that would be mainly for books in libraries overseas?

  3. That's where I've seen it. In Spain they call it Clasificación Decimal Universal.