The Keyword Authority Control or SWD is a controlled keyword or descriptor system (subject indexing

Subject indexing

Subject indexing is the act of describing or classifying a document by index terms or other symbols in order to indicate what the document is about, to summarize its content or to increase its findability. In other words, it is about identifying and describing the subject of documents...

), that is mainly used for indexing in libraries. The SWD is managed by the German National Library

German National Library

The German National Library is the central archival library and national bibliographic centre for the Federal Republic of Germany...

 (DNB) in cooperation with various library networks. The inclusion of keywords in the SWD is defined by "Rules for the Keyword Catalogue" (RSWK). Similar systems in other languages are the Library of Congress Subject Headings

Library of Congress Subject Headings

The Library of Congress Subject Headings comprise a thesaurus of subject headings, maintained by the United States Library of Congress, for use in bibliographic records...

(LCSH) and the Répertoire d'autorité-matière encyclopédique et alphabétique unifié (RAMEAU).

Scope

The SWD has about 600,000 descriptor

Descriptor

Descriptor may refer to*file descriptor, an abstract key for accessing a file*index term, also known as a "descriptor" in information retrieval*molecular descriptor, which helps characterize a chemical compound...

s and 700,000 non-descriptors (synonym

Synonym

Synonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...

s and quasi-synonyms) as well as synonymous descriptor chains with references to a descriptor. Its growth rate is about 5.5% per year. About three-quarters of the descriptors refer to individual concepts (language identifier, person, entity, title, ethnography ...) and a quarter are abstract concepts. Linking using hierarchical (about 115,000) and associative (26,000) relations is not very dense, so the SWD cannot be viewed as a thesaurus

Thesaurus

A thesaurus is a reference work that lists words grouped together according to similarity of meaning , in contrast to a dictionary, which contains definitions and pronunciations...

(as at mid-2003).

The terms in the SWD are also arranged in a separate classification

Classification

Classification may refer to:* Library classification and classification in general* Taxonomic classification * Biological classification of organisms* Medical classification* Scientific classification...

 with nearly 500 classes in 36 main groups.

Structure

The various terms are placed in a classification scheme and also contain references to sources, related terms, preferred term and to a lesser extent hierarchical links. But the SWD is probably not a complete thesaurus because of the low degree of linkage. The SWD is available online through the catalogue database ILTIS and are available, for a fee, as BIBLIODATA together with the Personal Name File (PND) and the Common Corporation File (GKD) on the standard data CD-ROM and the standard file TITAN. In both cases, the user interface of the SWD unfortunately leaves much room for improvement. Instead of making SWD accessible as a user-friendly navigation tool, it assumes that users are familiar with SWD and its classification scheme and enter the appropriate descriptor in the correct form before running a search. Navigating the system or moving from one concept to another by means of hyperlinks is not possible. The strategy of the German Library, to distribute authority records commercially, makes the extended use of the SWD difficult, e.g. in other keyword systems.

For the exchange of authority records, there is a separate Machine Exchange Format for Libraries (MAB) format. The head official of the Southwest German Library Network (SWB) offers online access (OSWD).

External links

• Searching the OSWD
• Information pages of the DNB about the SWD
• Rules for the Keyword Catalogue (RSWK) 3rd edition, Deutsches Bibliotheksinstitut, 1998
• Homework on the SWD