The Dewy Decimal System

This library classification system is easy to understand and easy to use, but has limitations. It is a system developed by Melvil Dewey around 1876 for the orderly classification books by topic. It’s been updated many times and the complete system is maintained by the Online Computer Library Center of Dublin, Ohio. They currently own the trademark for the classification system.

The Basic divisions of the system

The Dewy Decimal System is easy to use because its basic divisions are so simple they can be memorized. Compared to the primary alternative, the Library of Congress system, it is very easy to understand and consistent at every level.

There are ten primary headings. Each of those headings is divided and subdivided using the numbers which follow. The Primary divisions are as follow:

• 000 – Generalities
• 100 – Philosophy and Psychology
• 200 – Religion
• 300 – Social Sciences
• 400 – Language
• 500 – Natural Science and Mathematics
• 600 – Technology (Applied Sciences)
• 700 – The Arts
• 800 – Literature and Rhetoric
• 900 – Geography & History

Sub-categories

So then, there is room for 99 sub-categories under each of these primary divisions. Each of them is assigned by the Online Computer Library Center (OCLC) who maintains the system, updates it regularly, and holds the trademark on the system.

Each of those sub-categories is further divided using a series of decimals to more specifically classify each individual book.

The Cutter number

As the number of books in a collection grows, it is likely that there will be more than one book with the exact same classification, right down to the last decimal. In order to maintain a unique number for each text, a cutter number is added. This number is a combination of letters and decimals, developed by Charles Cutter, to enable the alphabetic arrangement to be maintained.

If there are several books in the same classification, written by the same author, one or more letters may be added after the cutter number to distinguish between the different titles. Cutter numbers are also used in the Library of Congress system.

Commentaries, Critiques, Copies and Editions

Sometimes there is a third line in the call number. This may be the cutter number of the author who is commenting on book with the call number indicated by the previous 2 lines. If there are two different editions, a year may be the next line of the call number. Last of all, multiple copies may be indicated by a c.1, c.2, or c.3 indicator.

Prefix

Occasionally libraries use a prefix to indicate a particular location for the book. Examples of this might be a line above the call number with R to indicate reference, L to indicate large print, or OS to indicate oversized items. The rest of the call number remains the same as if it were shelved in the main stacks of the collection.

Classification of Fiction texts

Books categorized as fiction are generally not catalogued according to this system, though there is a place to put them under the 800’s (literature). Most libraries choose instead to catalogued works of fiction alphabetically using the cutter numbers alone.

Still the choice for smaller collections

The Dewey Decimal System was used almost exclusively until the 1960’s when larger libraries started to move to the Library of Congress system which has a larger number of topical headings. Dewey is still the first choice among smaller libraries, church libraries and many schools.