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: ML

• 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: 410

• The numbers that immediately follow the first letters represent the specific subject within the larger subject area. See the Library of Congress's description of the M class 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(s): .A638 A3

• 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 this 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: 1945

• Sometimes, Cutter numbers will be followed by other information to help distinguish one item from another.
• In this case, 1945 follows the second Cutter number, and it differentiates this book from other editions of the same book.
• 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.