Auxiliary tables in the UDC

One of the principal features of Otlet's original scheme was the introduction of auxiliary tables. These auxiliary tables provide an economical way of scheduling the sort of terms that occur over and over again in the subjects of documents. When we looked at LCC we saw that concepts such as periodicals or geographical treatment were repeated very many times in the schedules, and that this repetition leads to very lengthy schedules. In UDC such terms are listed only once, in a series of special tables which can be used to qualify classes in the main tables. Although other schemes do make use of auxiliaries, UDC is unusual in the number of tables that it provides.

The auxiliaries in UDC greatly increase the specificity that you can achieve in subject description, and they are one way in which very detailed and expressive classmarks can be built.

The tables which can be applied to any classmark throughout the scheme are known as systematic auxiliary tables. Other auxiliaries exist which are used only in particular subjects, and they are called special auxiliary tables.

Systematic auxiliaries

The systematic auxiliaries provide for:

There are three tables concerned with form, and they cover:

You will notice that these are concepts that don't tell us anything about the content of a document, but they are nevertheless useful to express since readers may look for them.

The rest of the systematic auxiliaries deal with subject-related concepts. You'll remember some of these concepts from the chapters on content analysis. The common subject concepts include:

Each of these auxiliaries is introduced by its own particular symbol, and we'll look at each in turn. Generally, you can add a systematic auxiliary directly to the main table number which it qualifies. Because each auxiliary has a distinctive symbol to introduce it you don't need to alter either the main table number or the auxiliary when you're adding them together.