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Each book in the library has a unique call number. A call number is like an address: it identifies where the book is located in the library. Call numbers appear on the spine of books, bound periodicals, microfilm, and other items.  The UCR Libraries, like many university libraries, uses the Library of Congress Classification for call numbers. This system uses a combination of letters and numbers to arrange materials by subjects, and may appear in two different formats as seen below.

Read a call number by sections, line-by-line:

The first part of a call number contains letters. These letters are read alphabetically:

The second part of the call number contains numbers which are read as a whole number:

This second part of the call number may also contain a decimal component:
 

     

The third part is the trickiest part of all.  It consists of a single letter and then a sequence of numbers.  Items are placed first in alphabetical order by the letter, then numerically according to the sequence of numbers.   However, all numbers in this line are treated as if they were preceded by a decimal:

This makes sense if you read the numbers as decimals, because:

Location Prefixes
Some call numbers are preceded by a location prefix indicating that the item is shelved in a specific location and may have loan restrictions. For example:

Ref - Reference item located on the Reference shelves on the 1st floor.

Oversize - Large or oversized items shelved in the Oversize sections on each floor.