Introduction

Library classification organizes documents, not knowledge in the abstract. Therefore, in addition to the primary element of subject, classification also must consider the features of documents that indicate how the subject is treated therein. Library classification may thus be defined by the equation: subject + form of presentation + author's viewpoint + physical medium or form.

In practice, however, these aspects or facets are not always expressed in the class number; some facets are given priority over others, while some may be ignored, or only indicated in the catalog record.

Nomenclature

Standard subdivisions represent the non-primary or non-subject characteristics of documents. The DDC Glossary defines them as ‘Subdivisions found in Table 1 that represent frequently recurring forms (dictionaries, periodicals) or approaches (history, research) applicable to any subject or discipline’. Standard subdivisions were first recognized and listed in the Second Edition (1885). They have remained a constant feature of the system and their variety and importance have increased steadily. Originally, they were aptly known as ‘form divisions’, but eventually that term became inappropriate. The present name of standard subdivisions was given in the 17th Edition (1965). These are called Standard because their name and notation are constant, though exceptions are noted when appropriate.

Categories

The standard subdivisions as they stand today may broadly be categorized as:

Over time, the scope of the standard subdivisions has been widened so much so that it is better to go through the entire Table 1 to see their variety.

Characteristics of standard subdivisions

Standard subdivisions usually represent recurring non-primary characteristics of a document and non-topical characteristics that pertain to the document itself rather than to its primary subject.

For instance, in a title A History of Mathematics, the primary element is mathematics and history a non-primary element – making the full subject the history of mathematics. On the other hand, in A Dictionary of American History, the core subject is American history, the concept of dictionary does not affect the subject of the item; it pertains to the form used to present the material, not to the information found therein. Such distinctions may seem esoteric to begin with, but they are important in subject analysis and consequently in assigning the proper DDC number when standard subdivisions are required.