Library of Congress Classification

Call numbers in the Library of Congress Classification system (LC) are evaluated one line at a time from top to bottom. LC uses an alphanumeric system with letters followed by numbers.

Example:  
NA
3552
.B46
M27
1976
The number may also be written horizontally as:  NA 3552 .B46 M27 1976

Line 1.

NA is the first breakdown of the call number to be evaluated.  This is ordered in alphabetical manner as in the following sequence:

In other words, all NA books come before P books, etc.

Line 2.

Once the NA area is located, narrow the search using the second line. This line is a whole number, NOT a decimal number.  The second line (3552) is therefore shelved numerically.

Line 3.

The third line of this LC call number (.B46) is preceded by a decimal and is shelved as a decimal.

Line 4.
If the line includes both letters and numbers (as in the example), shelve exactly as in Line 3.  That is, letter first and number decimally.

If line 4 does not begin with a letter, the number is shelved as a whole number, just as in Line 2.

Additional Lines
Lines beyond the fourth line will NOT be shelved decimally.  Usually this number will be a publication date.

Shelving order for "years"
                    No date ( and "n.d.") is shelved before the same call number with a date.
                    1906 comes before 1907, etc.

Some call numbers will have more lines.  These may designate a volume, copy, or part number.  These are ordered in traditional numerical order, with 1 coming before 2, 2 before 3, etc.


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