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Library of Congress Call Numbers for Music: Reading the Numbers

A brief description of how Library of Congress (LC) numbers work for music

Reading an LC Call Number

The Music Library uses Library of Congress call numbers (also referred to as LC call numbers) for books and scores. These are made up of a number of components. Understanding each component can help you to read call numbers more easily. Let’s start with a sample call number and work through the individual parts.

ML 410 .A638 A3 1940
Author: George Antheil
Title: Bad Boy of Music
An autobiography by George Antheil

Initial Letters

  • The first letter(s) of a call number represents its subject area and, in music a bit about format as well:
    • M – music scores
    • ML – books of literature on music
    • MT – books of music instruction and study
  • In this case, the first two letters are ML, which means this is a book that contains literature on music.


Subject Numbers

  • The numbers that immediately follow the first letters represent the specific subject within the larger subject area. See http://www.loc.gov/aba/cataloging/classification/lcco/lcco_m.pdf for a break down of what these numbers represent in the music call numbers.
  • In this example, 410 indicates a commonly used subject designation, composer biography.
  • Sometimes, you will see this number written or typed on the same line as the intial letters; sometimes it will be on the next line down.  Such placement does not affect the sorting order of the call number or the item's placement on the shelf.


Cutter Number

  • The next number, referred to as the Cutter number, reflects a letter/number combination that the library has developed to indicate the author (or sometimes the topic) of a work and to ensure that similar works will be placed together on the shelf. It begins with a letter and is followed by numbers.
  • In the above example, the Cutter number is A638, which is the Cutter number that will be used for all books by George Antheil located in this section, the ML 410s.
  • Occasionally, you will see a book with a second Cutter number to define subject matter more clearly. In this example, A3 is a second Cutter number that refers to the subject matter (also George Antheil, since this is an autobiography).
  • Often, the Cutter number will be written with a decimal point preceding the letter (as in the example above), but sometimes there will be no decimal point.  The presence or absence of a decimal point has no effect on shelving order.


Additional Information

  • Sometimes, Cutter numbers will be followed by other information to help distinguish one item from another.
  • In this case, 1940 follows the second Cutter number, and it differentiates this book from another edition of the same book published in 1945 (ML 410 .A638 A3).
  • Other examples of additional information that might appear after the Cutter number include volume number, copy number, part name (such as trumpet or piano), or opus number.