How to build a Dewey Decimal number?

How to build a Dewey Decimal number?

How to Build a Number in DDC Classification: A Guide for Library Science Students and Professionals

The Dewey Decimal Classification (DDC) system is one of the most widely used methods for organizing library materials. Created by Melvil Dewey in 1876, the system organizes knowledge into ten main classes, with each class further divided into divisions and sections. A crucial aspect of using the DDC is assigning numbers to library materials to ensure they are accurately categorized and easily accessible.

Building a DDC number might seem complex at first, but once you understand the principles behind it, the process becomes much clearer. In this article, we’ll guide you through the steps of constructing a DDC number, offer practical examples, and discuss common challenges in library classification.

What is DDC Classification?

The Dewey Decimal Classification system is a hierarchical structure for categorizing books and other library materials. It is based on dividing human knowledge into ten major categories, each represented by a number ranging from 000 to 999.

  • 000–099: General Works
  • 100–199: Philosophy and Psychology
  • 200–299: Religion
  • 300–399: Social Sciences
  • 400–499: Language
  • 500–599: Science
  • 600–699: Technology
  • 700–799: Arts and Recreation
  • 800–899: Literature
  • 900–999: History and Geography

Each of these categories is further divided into subcategories, with more specific numbers assigned to reflect the subject matter of each work.

Steps to Build a DDC Number

Building a DDC number involves understanding the subject of the item being classified, choosing the appropriate class, division, and section, and possibly creating a more specific number by using decimal points to narrow down the subject. Below are the key steps to follow:

1. Identify the Subject of the Work

The first step is to fully understand the subject of the material you are classifying. Is it a book on psychology, a guide to photography, or a history of ancient Egypt? Knowing the subject will help you determine the correct broad class to start with.

2. Find the Broad Class

Once you know the general subject of the item, you can start by locating the broad class in the DDC. This will help you figure out which of the ten main classes it falls under.

For example:

  • A book on photography will belong in class 770 (Arts and Recreation → Photography).
  • A book on psychology will be classified under 150 (Philosophy and Psychology → Psychology).

3. Narrow Down to a Division and Section

After identifying the broad class, the next step is to narrow down the number to a more specific division or section. The DDC system breaks down each major class into more specific divisions. You can continue breaking down the subject further into narrower topics using decimal places.

For example:

  • A book on color photography would be classified as 779 (Photography → Techniques of Photography → Color photography).
  • A book on developmental psychology would be placed under 155.4 (Psychology → Developmental psychology).

4. Use Decimal Extensions for Specificity

In some cases, a subject may need to be even more specific. Decimal extensions allow for greater detail. This is done by adding more decimal places to the number.

For example:

  • 779.2 could be used for a book on portrait photography within the broader category of color photography.
  • 155.4 might be further extended to 155.424 for a specific book on child development.

5. Consult the Manual or Online Resources

If you’re unsure about the exact number to assign, always refer to the DDC Manual or WebDewey, which provide detailed guidelines on how to build numbers, special instructions, and exceptions for specific subjects.

Examples of DDC Number Construction

Let’s go through a few practical examples to better understand how to build a DDC number:

Example 1: A Book on World War II

  1. Subject: History of World War II.
  2. Broad Class: The subject is historical, so it belongs in the 900s range: 900 (History and Geography).
  3. Narrow Down: World War II is a specific historical event, so we look for the number that corresponds to it under history. We find 940.53 (History → History of Europe → World War II).
  4. Final DDC Number: 940.53

Example 2: A Book on Digital Photography

  1. Subject: Digital Photography.
  2. Broad Class: The subject relates to the arts, so it’s classified under 700 (Arts and Recreation).
  3. Narrow Down: Photography is found under 770 (Photography and photographs).
  4. Specific Topic: Digital photography is a technique within photography, so it is classified as 779 (Techniques of photography → Photographic processes).
  5. Final DDC Number: 779.1 (Techniques → Digital Photography).

Example 3: A Book on Plant Biology

  1. Subject: Plant Biology.
  2. Broad Class: Biology is part of the natural sciences, which falls under 500 (Science).
  3. Narrow Down: The subject of plant biology is classified under 580 (Plants and Plant Sciences).
  4. Specific Topic: A book on plant structure would be placed under 581.1 (Botany → Structure of Plants).
  5. Final DDC Number: 581.1

Challenges in DDC Classification

While DDC is an effective system, it is not without its challenges. Some common difficulties include:

1. Ambiguous Subjects

Some subjects may fit into more than one class, division, or section. In these cases, libraries need to decide based on the primary subject or the intended audience of the work.

2. New Subjects

As new knowledge and disciplines emerge, DDC may not always have an existing number to accommodate the new subject. Libraries may need to create a new number or use an existing number as a temporary solution.

3. Cultural and Linguistic Differences

DDC was designed with Western concepts in mind, which may cause issues when classifying materials from different cultures or languages. Libraries often adjust classifications to better fit local contexts.

Conclusion: Mastering the DDC Number Building Process

Building a number in the Dewey Decimal Classification system may seem complicated at first, but by following the basic steps and referring to available resources, it becomes much more manageable. Understanding how to break down subjects and use decimal extensions effectively is key to mastering DDC.

By classifying materials accurately, libraries can help users quickly locate resources and facilitate better access to knowledge. Whether you’re a library science student or a professional librarian, mastering the process of building a DDC number is an essential skill for effective library management.

This guide should help both beginners and professionals navigate the process of building DDC numbers with confidence and precision. Happy cataloging!

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