Page 96 - DLIS002_KNOWLEDGE ORGANIZATION CLASSIFICATION AND CATALOGUING THEORY

Unit 5: Universal Decimal Classification (UDC)

Self Assessment Notes

State whether the following statements are true or false:
5. Not all branches of human knowledge have a place in UDC.

6. UDC’s most innovative and influential feature is its ability to express not just simple
subjects but relations between subjects.

5.4 Notation

The symbols chosen for UDC notation are non-language-dependent, and universally recognizable
- the Arabic numerals, supplemented by a few other signs familiar from mathematics and
ordinary punctuation. They are not only easily readable, but easily transcribable using ordinary
office machinery such as typewriters and computer keyboards.

The arrangement is based on the decimal system: every number is thought of as a decimal
fraction with the initial point omitted, and this determines the filing order; but, for ease of
reading, it is usually punctuated after every third digit. Thus, after 61 ‘Medical sciences’ come the
subdivisions 611 to 619; under 611 ‘Anatomy’ come its subdivisions 611.1 to 611.9; under 611.1
come all of its subdivisions before 611.2 occurs, and so on; after 619 comes 62. An advantage of
this system is that it is infinitely extensible, and when new subdivisions are introduced, they
need not disturb the existing allocation of numbers.

5.4.1 The Tables

There are two kinds of table in UDC:

1. The main tables (also called the ‘schedules’): these contain the outline of the various
disciplines of knowledge, arranged in 10 classes and hierarchically divided.

2. Auxiliary tables, including certain auxiliary signs. The signs (e.g. the plus, the stroke, the
colon) are used to link two (or more) numbers, so expressing relations of various kinds
between two (or more) subjects. The enumerative tables denote recurrent characteristics,
applicable over a range of subjects; the auxiliary is simply added at the end of the number
for the subject. The most general of them, called common auxiliaries, are applicable
throughout the main tables, and represent notions such as place, language of the text and
physical form of the document, which may occur in almost any subject. There are also
more restricted series, called special auxiliaries, which express aspects that are recurrent,
but in a more limited subject range. They are therefore listed only in particular sections of
the main tables.

5.4.2 Parallel Division

Parallel division is a way of creating mnemonic consistency in the classification. Where the
same array of concepts is involved in more than one context, there is no point in arranging them
differently in each place. It is more helpful to the user if they are predictable – in the same order,
and similarly numbered; so there are many places in UDC where a sequence of numbers has the
same final digits as another sequence elsewhere, listing analogous concepts. This also means
that there is no need to list them fully in both places – the concepts can be enumerated once, and
entries in other places can indicate that parallel division is available. This simply means that a
given number can be subdivided in parallel with a second number, resulting in an exactly

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