M is for music, specifically, sheet music for solo instruments and any small or large ensembles. All the materials here are scores.
ML is for music literature. These materials are about music and musicians.
MT is officially for music instruction but it's easiest to remember it by music teaching. Materials found here will all be about teaching music from books about teaching to method books with collections of pieces.
The first set of numbers is called the subject number. This is how we keep materials about the same subject next to each other. For example, ML410 is the call number for music biographies. These are read as full numbers meaning the shelf order is 1, 2, 3, 4, etc.
The cutter number is the letter and number after a decimal or on the next row on the call number sticker. This number is usually a topic or an author. For example, a biography about Beethoven would have the cutter number .B4 for Beethoven. A second cutter number for the author of the biography usually follows such as L597 for Lewis Lockwood, the author of the biography Beethoven: The Music and the Life.
The shelf order of cutter numbers is as decimals so .S473 (Roger Sessions) comes before .S53 (Dmitri Shostakovich). Even though four-hundred seventy-three is bigger than fifty-three, point four-hundred seventy-three is smaller than point fifty-three.
Sometimes there is also a date, volume number, opus number, part name, etc. These are ordered as full numbers.
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