Metadata Principle 3

Metadata Principle 3: Good metadata uses authority control and content standards to describe objects and collocate related objects.

Attributes of distributed objects should be expressed using standard controlled terms whenever possible. These include, but are not limited to, personal names, corporate names, place names, titles of works, subjects, and genre headings. Names and titles should be formulated according to standard descriptive cataloging rules; subject and genre terms should be taken from controlled vocabularies and thesauri. Classification schemes, a form of controlled vocabulary that groups related resources into a hierarchical structure, can be useful in providing online subject access.

As with metadata schemes, there are many published thesauri, taxonomies, and authority files, and there is no “one-size-fits-all” solution. The choice of vocabularies to use will depend to some extent on factors such as the metadata scheme chosen, the nature of the collections being described, the resources of the institution, and user expectations. Factors to consider include:

  • The anticipated users of the digital collection. Will they be adults or children, specialists or generalists? What languages do they speak? What other resources are they likely to use, and what vocabularies are employed in those? 
  • Tools to support the use of the vocabulary. Is there an online thesaurus? Can it be incorporated into the collection’s search system? Are there cross-references and related terms? 
  • Maintenance. New terms come into use, and old terms become archaic or obsolete. Who maintains the vocabulary, and how are updates issued? 

To enable the most effective end-user access, the implementation of local, collection-specific authorities and vocabularies in addition to the use of terms and names from standard published authorities is often the best strategy. Whatever combination of vocabularies is chosen, their use should be carefully documented and in-house guidelines should be provided to help metadata creators select terms consistently. Authors and other untrained metadata creators cannot generally be counted on to use controlled vocabularies successfully unless the authority list is very short and simply organized.

The High Level Thesaurus Project (HILT, is a clearinghouse of information about controlled vocabularies, including related resources, projects, and an alphabetical list of thesauri.

Some organizations maintain suites of thesauri for use within specific domains:

  • The Getty Vocabulary Program website The Getty builds, maintains, and disseminates several thesauri for the visual arts, architecture, and material culture. The Art & Architecture Thesaurus (AAT) is also available in Spanish ( and Dutch ( 
  • MDA, Terminology Bank website terminology/termbank.htm. The MDA (formerly known as the Museum Documentation Association) builds, maintains and disseminates thesauri for museum objects, including vocabularies for describing archaeological objects, waterways, railways, costumes, and aircraft types. 
  • Library of Congress Authorities website The Library of Congress builds, maintains, and disseminates authority files for bibliographic description, including a controlled list of subject headings and a file containing authorized forms of personal and corporate names, titles, and name/title headings. 

Some other controlled vocabularies are:

  • Revised Nomenclature for Museum Cataloging: A Revised and Expanded Version of Robert C. Chenhall’s System for Classifying Man-made Objects (Nashville: American Association for State and Local History, 1988). Not available on the Web, this resource is used by many small museums and historical societies. All of the terminology from Chenhall’s “Nomenclature” that falls within the scope of the Art & Architecture Thesaurus has been included in the AAT. 
  • ICONCLASS website A classification system, consisting of alphanumeric notations, textual correlates, and related keywords, for describing the narrative and iconographic content of works of art and other visual materials. The master version is in English; German, Italian, French, and Finnish translations are also available. 
  • Thesaurus for Graphic Materials (TGM) I: Subject Terms (1995)
  • Thesaurus for Graphic Materials (TGM) II: Genre and Physical Characteristics Terms (2004)
  • U.S. Geological Survey, U.S. Board on Geographic Names’ Geographic Names Information System website

Classification systems available on the Web include:

  • Dewey Decimal Classification [Subscription required for access.] 
  • Library of Congress Classification [Subscription required for access.] 
  • OCLC’s Terminologies Service website Provides metadata- building tools combined with access to a range of controlled vocabularies and thesauri, including the Getty vocabularies, MeSH, and TGM I and II.  


Last updated: 04/17/2008