Dewey Decimal Classification : Brief Information of DDC

The Dewey Decimal Classification (DDC) system is a venerable cornerstone in library organization, providing an efficient and systematic approach to cataloging knowledge. Developed by Melvil Dewey in 1876, this classification system revolutionized how libraries arrange and retrieve information, offering a structured framework transcending linguistic and cultural barriers. Rooted in the principle of decimal notation, the DDC assigns a unique numerical identifier to each subject, facilitating the orderly arrangement of books and resources on library shelves. Over the years, the DDC has undergone revisions to accommodate the evolving landscape of human knowledge. Yet, its enduring legacy is a testament to its enduring relevance in facilitating access to vast information in libraries worldwide.

1.1 History of Dewey Decimal Classification (DDC).

The Dewey Decimal Classification (DDC) system is a general knowledge classification tool used in library classification that is continuously revised to keep pace with current knowledge. This system was first published in the United States of America by Melvil Dewey in 1876. Currently, DDC is published by OCLC (Online Computer Library Center), the world’s most widely used classification system, translated into more than 30 languages. It has been revised and expanded through 23 major editions, the latest issued in 2011.

Dewey Decimal Classification (DDC) is the most popular of all the modern library classification schemes. It was devised by Melville Dewey in 1876. It provides a systematic arrangement of all the materials mechanized by the notation of great simplicity and apparent flexibility. With the emergence of DDC, the principle of the relative location of books on a shelf according to the subject became perfectly feasible, and it replaced the then-existing practice of a fixed location when a certain number of shelves were allotted to each subject, and each book was identified by the shelf number and its position on the shelf. As a matter of fact, all our decimal fraction notation, but for the convenience of remembering the number, the decimal point is inserted after the third digit. Sub-divisions are carried out decimally, and all numbers are read as decimals. At each stage, there are nine coordinate divisions. Whenever there are more than nine divisions of equal status, the eight are named, and the remaining are covered in the nine divisions, i.e., ‘others’. The use of simple and pure notation, Indian numbers, provision of form division, and relative index has made DDC very popular.

1.2 Different Editions of DDC:

1.3 Features of the Dewey Decimal Classification:

Decimal Classification is an almost enumerative scheme of classification. Since 1876 to 2011(23^rd edition), this scheme did not look back, and its popularity has grown worldwide. This statement can be justified by the fact that DC has been translated into many languages, such as Chinese, Spanish, Danish, Turkish, Japanese, Hindi, Portuguese, Sinhalese, and several other languages across the globe. Dewey introduced the notion of using notation for the subjects in his scheme and applying the notation to the book and not to the shelves. But certain features forming the basis of its present form can still be recognized as follows:

1. Universal Scheme: A distinctive feature of the DDC is that its classes reflect all the areas of specialized knowledge developed in modern society. These specialized areas are loosely put together in the main classes in the scheme, and in this manner, the principle of collation of bringing related subjects in close proximity is sometimes violated.
2. Relative Location: In his scheme, Melvil Dewey introduced the brainwave of’ relative location’ instead of ‘fixed location.’ For this purpose, heutilized the decimal notation consisting of Arabic numerals for the subjects and assigning that notation to the books based on thought content and not based on the shelves. In this method, a new book on a given subject may be put in between the existing sequence at the required position, directed by the notation assigned to that book, and there is no necessity to put the book at the end of the sequence as had been the practice in “fixed location.”
3. Decimal Notation: Melvil Dewey used decimal fraction notation to arrange knowledge on the shelves. Indo-Arabic numerals (0 to 9) are used decimally for the sub-divisions of knowledge. In this process, the universe of subjects is divided into ten main classes, each of which is again divided into ten divisions. Again, each division is further divided into ten sections. At each stage of division, a given number is subdivided decimally. All the class numbers in DDC are decimal fractions.
4. Minute Division: The first edition of DDC consisted of only 42 pages, and at that time, it was criticized for being too broad in its sub-division. The number of pages has since increased, as shown in Table 1. This growth suggests the enormous number of possible and useful sub-divisions for minute classification. Dewey emphasized the need for minute division as “the advantage of close classing is unquestioned if the user knows just what it is.”
5. Mnemonics: Another important feature of DDC is mnemonics, which means ‘aid to memory.’ In DDC, mnemonics are available for subject synthesis. The use of consistent order in the subject division of different classes produces mnemonics. Various tables, such as area tables, language tables, standard division tables, etc., are used to achieve subject synthesis. The user may also find Scheduled Mnemonics, Systematic Mnemonics, and Alphabetical Mnemonics at a few places in DDC.
6. Integrity of Numbers: One of the most important features of DDC is the integrity of numbers. To incorporate new developments and keep pace with the growth of knowledge, a classification scheme should be revised continually, without changing the basic structure, so that the professionals may accept the revised edition without hesitation.
7. Auxiliary Tables: Auxiliary tables provide an important basis for preparing numbers and lead to uniform meanings of numbers when used in various contexts. A document, which is a source of knowledge, always has some physical form. Melvil Dewey, in the second edition of the scheme published in 1885, introduced the concept of “Form Divisions” to be used for the sub-divisions of a subject based on the characteristics of documents, either in accordance with the point of view of the author, i.e. Bibliographical, Philosophical, Theoretical, Historical or in accordance with the form of thought content in documents, i.e. Digest, Manual, Monograph, Dictionary, Periodical or Manual. The “form divisions” could be attached to any class number according to the instructions provided therein. The ‘form divisions’ system remained in use until the 12^th edition. The 13^th edition consisted of 5 “Auxiliary Schedules.” The 14^th edition had 4 tables. In the 15^th edition, the conventional 9 form divisions, i.e., 01-09, were annexed along with the tables, without any detailed sub-divisions. The word ‘Form divisions’ was replaced by“Standard Subdivisions’ in the 17th edition, along with a new area table in volume 2(Index). The 18^th, 19^th, and 20^th editions consist of 7 auxiliary tables detailed under DDC 20.

1.4 Structure of Dewey Decimal Classification:

1. Schedule: A basic premise of DDC is that it is arranged by discipline and not by subject. At the broadest level, the DDC is divided into ten main classes that cover the entire world of knowledge. Each main class is divided into ten divisions, each into ten sections (not all the numbers for the divisions and sections have been used). The three summaries of the DDC are as given:
2. Summaries: Summaries provide an overview of classes’ intellectual and notational structure. Three types of summaries appear in the schedules and tables of DDC. The summaries of the schedules as a whole are found at the front of the schedules (Volume 2-3). Single-level summaries in the schedules and tables provide an overview of classes with sub-divisions extending over two pages. Multi-level summaries are provided for eight major divisions, and the Area Tables are for Europe and North America.

The First Summary Contains the ten main classes. The first digit in each three-digit number represents the main class.

The Second Summary: Contains the hundred divisions. The second digit in each three-digit number indicates the division.

The Third Summary contains a thousand sections. The third digit in each three-digit number indicates the section. Thus, 530 is used for general works on physics, 531 for classical mechanics, 532 for fluid mechanics, and 533 for gas mechanics. Arabic numerals are used to represent each class in the DDC. A decimal point follows the third digit in a class number, after which division by ten continues to the specific degree of classification needed.

DDC Relative Index:

The relative index is appended to the schedules of book classification. It is the most important feature of this scheme; it is arranged alphabetically, and it aims to include all topics expressed or implied in the main tables together with every likely synonym. The index is comprehensive but exhaustive. The topics further sub-divided in the table are entered in the boldface type. The specific items in the sub-divisions are entered directly under their name. The index is relative in that each phase of the subject is noted. If a topic is treated in two or more classes, the number it takes in each group is taken. The use of the index is not limited to locating topics in the tables; it has equal value in locating topics on the shelves and in fact the reader’s key to the shelf arrangement in every library in which the DDC is being used.

Revision of the Scheme:

The main method of revision has resulted from the publication of new editions. Revisions usually take the following forms: Expansion, Relocation, and Reduction and Phoenix schedules. The last form is the most far-reaching form of revision. However, “DDC & Decimal Classification: additions, notes and decision’ is a beneficial means by which modifications can be announced before a forthcoming latest edition.

References: (This document is collected from materials available from online/web and organize here for LIS students)

1. KRISHAN KUMAR. Theory of classification. 1993. Vikas Publishing; New Delhi. p1.
2. SHARMA (C D). Use of libraries: A guide to better use of libraries and their resources. 1978. Metropolitan Book; New Delhi. p-120.
3. SHARMA (C D). Op. cit., p 121.
4. KRISHAN KUMAR. Op. cit., p 4.
5. INDIRA GANDHI NATIONAL OPEN UNIVERSITY (IGNOU). Unit 2: Needand purpose of library classification. IGNOU; New Delhi. p 26.
6. DUTTA (Dwijendranath). Library classification: Theory and practice. 1962. The Western Book Depot; Nagpur. p 48.
7. RAJU (Addepali Appala Narasimha). Dewey decimal classification (DDC 20): Theory and practice: A practical and self instructional manual. 1995. T.R. Publications; Madras. p 4.
8. CHOWDHURY (G G). Introduction to modern information retrieval. Ed. 3. 2004. Facet Publishing; London. p 89.

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