Page 75 - DLIS002_KNOWLEDGE ORGANIZATION CLASSIFICATION AND CATALOGUING THEORY

Knowledge Organization: Classification and Cataloguing Theory

Notes The second summary contains the hundred divisions. The second digit in each three-digit number
indicates the division. For example, 600 are used for general works on technology, 610 for
medicine and health, 620 for engineering, and 630 for agriculture.
The third summary contains the thousand sections. The third digit in each three-digit number
indicates the section. Thus, 610 are used for general works on medicine and health, 611 for
human anatomy, 612 for human physiology, 613 for personal health and safety.

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. A subject may appear in more than one discipline.

Example: “Clothing” has aspects that fall under several disciplines. The psychological
influence of clothing belongs in 155.95 as part of the discipline of psychology; customs associated
with clothing belong in 391 as part of the discipline of customs; and clothing in the sense of
fashion design belongs in 746.92 as part of the discipline of the arts.

4.6.2 Hierarchy

Hierarchy in the DDC is expressed through structure and notation. Structural hierarchy means
that all topics (aside from the ten main classes) are part of all the broader topics above them. Any
note regarding the nature of a class holds true for all the subordinate classes, including logically
subordinate topics classed at coordinate numbers.
Notational hierarchy is expressed by length of notation. Numbers at any given level are usually
subordinate to a class whose notation is one digit shorter; coordinate with a class whose notation
has the same number of significant digits; and superordinate to a class with numbers one or
more digits longer. The underlined digits in the following example demonstrate this notational
hierarchy:

600 Technology
630 Agriculture and related technologies
636 Animal husbandry

636.7 Dogs
636.8 Cats
“Dogs” and “Cats” are more specific than (i.e., are subordinate to) “Animal husbandry”; they
are equally specific as (i.e., are coordinate with) each other; and “Animal husbandry” is less
specific than (i.e., is superordinate to) “Dogs” and “Cats”. Sometimes, other devices must be
used to express the hierarchy when it is not possible or desirable to do so through the notation.
Special headings, notes, and entries indicate relationships among topics that violate notational
hierarchy.

4.6.3 Arrangement of the DDC

The print version of the latest full edition of the DDC, Edition 22, is composed of the following
major parts in four volumes:

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