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Subject Headings

Authorities and vocabularies / Library of Congress
SKOS version: The primary goal of this service is to enable machines to programmatically access data at the Library of Congress but the web interface also provides simple user access. MARC version:


Authorities - VIAF / Virtual International Authority File


ClassWeb includes LCSH (Library of Congress Subject Headings)


SACO Participants' Manual - 2nd ed. / Adam Schiff


Subject Authority Cooperative Program (SACO) SACO provides a means for libraries to submit subject headings and classification numbers to the Library of Congress.


Library of Congress Subject Headings (LCSH) approved lists (monthly)


Library of Congress Subject Headings browsing tools / B. Eversberg Explanation and links - lcsh/ Boolean search option - lcsh/detail.php


Thesaurus for Graphic Materials / Library of Congress As of October 2007, the Thesaurus for Graphic Materials I: Subject Terms (TGM I) and the Thesaurus for Graphic Materials II: Genre and Physical Characteristic Terms (TGM II) were merged into a single vocabulary,the Thesaurus for Graphic Materials,and migrated to new software. Application guidelines for genre/format terms (TGM II) and a separate genre/format term list for downloading will continue to be available at the TGM II home page".


Canadian Subject Headings  CSH on the Web - CSH is a list of standard subject headings (in English) on Canadian topics, which complements Library of Congress Subject Headings ( LCSH)


IFLA Section on Classification and Indexing The Section focuses on methods of providing subject access in catalogs, bibliographies, and indexes to documents of all kinds, including electronic documents. It serves as a forum for producers and users of classification and subject indexing tools.


654 Faceted subject headings - AAT application In the term records, the Hierarchy field is followed by a code in brackets, eg. [KT]. The first letter if input in $c preceding the $_term to which it applies. $c is mandatory. Example: $c k $b Spanish $c h $a engineers. $2 aat


Web Resources for SACO Proposals / PCC

Fiction and Genre

GSAFD file File gsafd.mrc.txt best viewed on Internet Explorer; stored by Gary Strawn at Northwestern Library's FTP server.


Demographic Group Terms Manual - draft Library of Congress Demographic Group Terms (LCDGT) manual:


LC Genre/Form Terms Manual - draft The instruction manual for Library of Congress Genre/Form Terms for Library and Archival Materials (LCGFT). The manual consists of guidelines and instructions for assigning genre/form terms and proposing new ones:


Juvenile literature / fiction / Materials intended for young readers LC's Descriptive Cataloging for Juvenile works: Subject Headings Manual H1690: 

  • Treat topical (non-fiction) materials intended primarily for children and young people through the age of 15, or 9th grade, as juvenile
  • Treat fiction intended primarily for children and young people through high school age as juvenile
  • Form Subdivisions

    Subdivision authority records (18X) / Cataloging Policy and Support Office As announced in March 1998 by the Cataloging Policy and Support Office ( CPSO), the Library of Congress has begun to create subdivision authority records to control the approximately 3,100 topical, form, and chronological free-floating subdivisions in the Library of Congress Subject Headings system. These records contain subdivision data in 18X fields and codes in 073 fields that identify their controlling instruction sheet numbers from the Subject Cataloging Manual: Subject Headings (H 1095 - H 1200).



    LCSH genre form headings, GSAFD, LCSH, LCGFT / Joel Hahn


    LCGFT - MARC Genre/form code and term source codes


    LCGFT - Library of Congress Genre-Form Thesaurus (LCGFT) for Moving Images: Best Practices / OLAC


    LCGFT - Music Library Association Best practices


    LCMPT - MARC Music instrumentation and voice code source codes


    LCMPT - Best practices / Music Library Association Terms listed in Classification Web


    LCDGT - MARC Genre/form code and term source codes Occupation Term Source codes: sourcelist/occupation.html Gender Code and Term Source codes: sourcelist/gender.html Subject Heading and Term Source codes include LCDGT: sourcelist/subject.html


    Moving Image Genre-Form Guide / Motion Picture/Broadcasting/Recorded Sound Division, Library of Congress It defines the concepts of form and genre separately. It makes those definitions operational by providing separate lists of terms. Terms from the form and genre lists are combined in a faceted manner.


    Moving Image Genre-Form headings / OLAC

    LC Announcements

    Summary of Decisions / Library of Congress / SACO


    Library of Congress Cataloging and Acquisitions (ABA) home including news and subject and genre/form headings information

    Other Thesauri

    BISAC subject headings list, major subjects:


    Fact Sheet : UMLS � Metathesaurus � The UMLS Metathesaurus is one of three knowledge sources developed and distributed by the National Library of Medicine as part of the Unified Medical Language System� (UMLS�) project. The Metathesaurus contains information about biomedical concepts and terms from many controlled vocabularies and classifications used in patient records, administrative health data, bibliographic and full-text databases and expert systems.


    Fact Sheet : Unified Medical Language System In 1986, the National Library of Medicine (NLM), began a long term research and development project to build a Unified Medical Language System� (UMLS�). The purpose of the UMLS is to aid the development of systems that help health professionals and researchers retrieve and integrate electronic biomedical information from a variety of sources and to make it easy for users to link disparate information systems, including computer-based patient records, bibliographic databases, factual databases, and expert systems.


    FAST / OCLC searchFAST FAST subject headings were developed by adapting the Library of Congress Subject Headings (LCSH) with a simplified syntax, retaining the very rich vocabulary of LCSH while making the schema easier to understand, control, apply, and use. Several indexes and the ability to restrict the result to a desired FAST facet increase searching accuracy. The default result ranking is by usage, giving the most likely candidate heading near the top of the result, although alphabetic and facet order options are easily available. An autosuggest makes the selection process even easier.


    NASA Thesaurus Text in PDF:


    Thesauri and Dictionaries / ABC 

    SAC Subcommittee on Semantic Interoperability


    Compiled report through March 4, 2006 (above)


    Program - Orlando 2004 See Enriching Subject Access (document below)


    Subject Semantic Interoperability: Final Report ALCTS Subject Analysis Committee, Subcommittee on Semantic Interoperabililty

    Articles, etc.

    ALCTS/CCS/SAC Subcommittee on Form Headings : Subdivisions Implementation, 1996-


    ALCTS CCS Subject Analysis Committee : subcommittees on metadata


    Application of form data to works of fiction : discussion paper / Andrew MacEwan ...


    Educational forum: LCSH and subfield v


    HILT - High-Level Thesaurus Project : building consensus for interoperable subject access across communities / Susannah Wake


    How Many Subdivisions Represent the Form of an Item? : Results of a Research Study / Arlene Taylor


    LC Action 2.3 Bates report summary (see document below)


    MetaSearch Initiative Metasearch, parallel search, federated search, broadcast search, cross-database search, search portal have become commonplace in the information community's vocabulary. They speak to a common theme of allowing search and retrieval to span multiple databases, sources, platforms, protocols, and vendors at once. One-search access to multiple resources holds the promise of enabling libraries to offer portal environments so their users can enjoy the same easy searching found in web-based services like Google.


    Subdivision report followup



    (compiled by Lois Mai Chan and Marcia Lei Zeng)



    ADL Thesaurus Protocol, University of California, Santa Barbara, USA
          Subject coverage: no limit

          Types of KOS involved: thesaurus

          Languages involved: English


          Status: operational, prototype

    The Alexandria Digital Library (ADL) Project at the University of California, Santa Barbara, focuses on the design and implementation of geospatial digital libraries and has been involved with the design and building of collections, services, and KOS since the beginning of the NSF DL funding in 1994 (ADL Homepage). In 2001-2002, the ADL Implementation team developed both a Gazetteer and a Thesaurus Service Protocol.   They are lightweight, stateless, XML- and HTTP-based protocols.   Both are designed to support programmatical searching and retrieval of distributed online resources. The Thesaurus Protocol is based on the ANSI/NISO (1993) Z39.19 thesaurus model and supports downloading, querying, and navigating thesauri.   Like the Gazetteer Service Protocol, all that is required for its use is the development of a thesaurus server that can accept the specified XML-encoded queries and return the specified standard reports.   Theoretically, once a server has installed the program and linked it to a potential thesaurus, it can search various thesauri distributed over the Web, receive and process protocol-type queries sent by special chains or by thesaurus lookup embedded in other programs (Jan  e, Ikeda, and Hill, 2002).

    CAMed, Columbia University and Kent State University, USA
          Subject coverage: alternative and complementary medicine

          Types of KOS involved: thesaurus

          Languages involved: English, French


          Status: prototype


    In an international collaborative project CAMed, a comprehensive resource for complementary and alternative medicine (CAM), researchers at Columbia University and Kent State University developed an integrated thesaurus management and cross-thesaurus search system.   In the prototype, four thesauri in the areas of CAM were normalized and stored in a thesaurus repository. This system allows a database manager to manage and edit his thesaurus in his local office (in his country) through the Web interface, while the thesauri are deposited and hosted on the server at Kent State University.   The cross-thesaurus search function of the system allows a user to type one term and search all or any of the thesauri in this repository.   Software matches the query against the thesauri and gives back all fully- or partially-matched thesaurus entries.   When a term is selected from the search results, a user can see the details of a thesaurus term entry (including the broader, narrower, and related terms, as well as non-preferred terms)   and continue selecting among the terms displays.   The term-search eventually enables a direct search in four bibliographical databases (samples) that have been integrated in the prototype.   The term search function also extends to the full-text searching of all resources in the CAMed website (Zeng and Chen, 2003).  



    CARMEN, Germany
                 Subject coverage: mathematics, physics, social science

                 Types of KOS involved: classification scheme, thesaurus

          Languages involved: German, English


          Status: Research and development


    CARMEN (Content Analysis, Retrieval, Metadata: Effective Networking), a specially funded project within the Global Info German Digital Library Project in Germany consists of several Work Packages (WP).  Its WP 12 is named   Cross concordances of classifications and thesauri  .  The emphasis in CARMEN is on mathematics and physics, but for methodological reasons the subject-oriented frame also include social sciences.  It began with correlating different German thesauri that are used to index social science literature through intellectual and statistical methods simultaneously. It also proposed to establish a concordance between the general classification, DDC, and special classifications,  including the Regensburger Verbund klassifikation (RVK) in the areas of mathematics and physics, the American Mathematical Society (AMS) Mathematics Subject Classification (MSC), and American Institute of Physics (AIP) Physics and Astronomy Classification Scheme (PACS) (CARMEN WP12, 2000).  One part of the CARMEN Project concerns itself with the association of the IZT (Informationszentrum Sozialwissenschaften=Information Centre for Social Sciences) thesaurus with the SWD (Schlagwortnormdatei). The method by which equivalencies are determined and links created is rather simple: starting from alphabetical lists which contain descriptors from a specific subject area, the relationships between the two thesauri are determined intellectually. Several thousand descriptors have been processed so that equivalent relationships between the thesaurus of the Informationszentrum Sozialwissenschaften, the thesaurus of the Deutsches Institut f  uerPaedagogische Forschung (German Institute for Educational Research), and the subject word authority file which was based on a unified scheme for subject heading, namely the RSWK (Regeln f  r dem Schlagwortkatalog), have been established and then recorded in a link management system (Kunz, 2002).


    Classification Web, Library of Congress, USA
          Subject coverage: general

          Types of KOS involved:   subject heading list, classification scheme

          Languages involved: English


          Status: operational


    For years, the Library of Congress of the United States has attempted to provide links between Library of Congress Subject Headings (LCSH) and Library of Congress Classification (LCC) numbers where appropriate.   Initially the links resided in LCSH only, but now they appear in linked LC classification authority records as well.   Under valid headings in the print version of LCSH, the equivalent LC classes or specific numbers are listed.     In the subject authority records for the terms in question, the corresponding class numbers are included.   In Classification Web (a web-based interface under development), the user can move across the schemes through the links between the class numbers and subject headings (Classification Web website, 2002).


    Finnish project, Finland              

    Subject coverage: general

          Types of KOS involved: classification scheme, subject heading list

    Languages involved: Finnish

          Status: operational


    Himanka and Kautto (1992) reported their work to convert assigned class numbers based on the Finnish abridged edition of UDC into General Finnish Subject headings (GFSH).   First, a dictionary is created that maps UDC numbers to subject headings.   Secondly, the dictionary is mechanically applied to convert the bibliographic databases.  


    HEREIN, Council of Europe


          Subject coverage: cultural heritage

          Types of KOS involved: thesaurus

          Languages involved: Spanish, French, English

    Website of the project:

          Status: operational through website:


    The HEREIN Project (European Heritage Information Network on cultural heritage policies) of the European Heritage Net has developed an interlingua with no direct reference to the terms or to the structure of any pre-existing thesaurus. (, select Thesaurus)   Most of the terms in the thesaurus come from reports on cultural heritage policies in Europe.   With these reports, each of the three teams    from Spain, France, and the United Kingdom -responsible for the establishment of the thesaurus created a separate list of terms in its own language. These lists were also supplemented with additional terms gathered from specialized documentary sources. The three teams then compared their lists so as to obtain a pool of words with linguistic equivalences in the three languages; the idea was to bring out the different classes intended to represent the first, broadest level. Each term selected was placed into the most relevant class. Within each class, terms were ordered following the same hierarchical relationship for all linguistic versions of the thesaurus. During this stage of work, terms regarded as too specific to one language and those reflecting regional idiosyncrasies were not excluded from the thesaurus but treated as equivalent terms to a concept common to all three languages.  

    In building the tri-lingual vocabularies within the HEREIN Project, the thesaurus follows the five types of equivalence relationships defined in the ISO (1985) 5964 standard: exact equivalence; inexact equivalence; partial equivalence; single-to-multiple term equivalence; and non-equivalence.   However, HEREIN deviates from the ISO 5964 standard in that it does not designate a source language (Th  rond, 2002).

    The project originally involved governmental services in charge of cultural heritage in six European countries, but the network was later expanded. The site was opened in 1999 and was concerned with collecting information on national heritage policies across Europe. In addition to the concise data, the site was also a portal to computerized databanks and selected Internet sites, and included a multilingual thesaurus in English, French and Spanish to index the databank and clarify the concepts (HEREIN 2 website).



    HILT (High-Level Thesaurus Project), UK       


          Subject coverage: general and special

          Types of KOS involved: thesaurus, classification scheme, subject heading list

          Languages involved: multiple languages


          Status: Research and Development


    HILT (High-Level Thesaurus Project) Phase I was funded by Joint Information Systems Committee (JISC) and the Research Support Libraries Programme (RSLP) of the United Kingdom, and HILT Phase II is funded by the JISC. HILT1, a one-year project initiated in September 2000 in U.K., investigated the problem of searching and browsing across a number of distributed services using different indexing vocabularies and attempted to derive a set of recommendations to help facilitate cross-searching and browsing by subject between communities, services, and initiatives. These included archives, the Further and Higher Education sectors, libraries, museums, the National Grid for Learning, and the Resource Discovery Network, etc., which usually use different subject schemes (HILT, 2000).

                      After completing a series of surveys on the main literature, stakeholders, and machine solutions and interfaces, a stakeholder workshop was held in 2001 for the purpose of reaching consensus on the best approach to address the issues.   A clear consensus emerged that the   best way forward   was to establish a pilot mapping service.   The proposed approach is to   map key schemes like LCSH, UNESCO, DDC, UDC (Universal Decimal Classification), AAT, and perhaps user and regional terminologies and local adaptations of standard schemes, perhaps using one of them such as DDC as the central spine of the approach   (Nicholson, Wake and Currier, 2001, Nicholson and Wake, 2003).     HILT1  s conclusions are: many different subject schemes and practices were in use; cross searching by subject was considered of value to users and staff; and an online terminologies route map or TeRM that would map subject schemes to user terminologies and to each other was the preferred solution.   HILT1 also concluded that there was a strong consensus favoring a project to create a pilot TeRM and investigate these issues.   HILT Phase II moves Phase I process into the 'Pilot Project' stage, focusing on terminology and thesauri requirements at the collection level, but also bearing in mind the need to extend this in due course to the needs of item level retrieval. The initial illustrative TeRM would be based on the RDN terminologies, on terminologies available as part of the Wordmap taxonomies set, which include, in particular, a set of terms used by general internet users, and on selective subsets of LCSH, DDC, UNESCO, and AAT. OCLC will provide an LCSH    DDC mapping, and may also be able to provide a DDC to Conspectus subject headings mapping. The aim would be a selective mapping sufficient for the purposes of the pilot in the first instance    i.e. not a comprehensive terminologies map (Nicholson, 2002).


    LCSH and MeSH, Northwestern University Libraries, USA
          Subject coverage: general, medicine

          Types of KOS involved: subject heading list

          Languages involved: English

          Status: Operational


    LCSH (Library of Congress subject headings) and MeSH (Medical subject headings) often co-exist in online public access catalogs (OPAC).   In an attempt to facilitate cross-vocabulary searching, the Northwestern University Libraries in the United States embarked on a project to map terms between these two vocabularies.   The method adopted is to first use automatic data processing methods to generate heading pairs that represent potential correspondences between LCSH and MeSH.   These heading pairs are then reviewed by subject editors to verify true correspondence.   The 7XX linking fields of the MARC21 authority format are used as linking mechanisms.   Thus, the mapping data reside in authority records.   The data is maintained by reviewing the weekly updates to LCSH and the annual updates to MeSH to find new, deleted, or changed headings, after which the mapping data is adjusted accordingly (Olson, 2003).

    In mapping terms, one-to-one correspondence is preferred.   These include identical/co-extensive headings, main heading to main heading/subdivision, and main heading to cross reference(s).   Since not all terms can be mapped precisely between the two vocabularies, various degrees of correspondence or matching are also recognized.   These include one-to-two and two-to-one correspondences (Olson, 2003).


    MACS (Multilingual   Access to Subjects), Europe

          Subject coverage: general

          Types of KOS involved: subject heading list

          Languages involved: English, French, German


    Status: operational            


    MACS is a European project designed to allow users to search across cataloging databases of the partner libraries in different languages: English, French, and German for the moment.   The partners are: the Swiss National Library (SNL), project leader, the Biblioth  que nationale de France (BnF), The British Library (BL) and Die Deutsche Bibliothek (DDB). The project is running under the auspices of the Conference of European National Librarians (CENL). It aims "to provide multilingual subject access to library catalogs," by establishing equivalence links among three subject headings lists: SWD/RSWK (Schlagwortnormdatei / Regeln f  r den Schlagwortkatalog) for German Rameau (R  pertoire d'autorit  -mati  re encyclop  dique et alphab  tique unifi  ) for French, and LCSH for English.   The method employed for mapping consists of comparing subject headings in three monolingual lists and checking the consistency of bibliographic records retrieved with these headings.   The links were analyzed on three levels: terminological level (subject heading), semantic level (authority record), and syntactic level (application).   For creating and maintaining link equivalences among the three vocabularies, a "link management" interface was developed.   It contains a classification field currently based on about sixty broad domains.   The use of a classification ensures the creation of homogeneous groups of headings by subject (Freyre and Naudi 2003).


    Megathesaurus - H.W. Wilson Company, USA

          Subject coverage: general and special

          Types of KOS involved: thesauri

          Languages involved: English

          Status: operational


    To facilitate multi-file searching across Wilson databases that have been indexed with different controlled vocabularies, the H. W. Wilson Company has developed and is maintaining a   megathesaurus,   in a sense, a thesaurus of thesauri.   Each record in the megathesaurus contains the   authority main term   or   megathesaurus term,   which serves as the anchor to which equivalent terms, along with their respective relational terms, from twelve vocabularies are mapped and stored. An automatic switching mechanism in searching has been developed, which enables the user to search a single index

      , multiple indexes simultaneously, or the combined indexes in the multi-file OMNI Index in a transparent manner, by using search terms based on any of the source vocabulary (Kuhr, 2003).


    Merimee, France

          Subject coverage: cultural heritage, art and architecture

          Types of KOS involved: thesaurus

    Languages involved: English, French


          Status: operational


    For the purpose of indexing complexes, buildings, and built works described in the national database "Merimee" about the French Heritage, The Thesaurus of Architecture (Le th  saurus de l'architecture) was created and mapped to the Art and Architecture Thesaurus (AAT,, published by The J. Paul Getty Trust) and the English Heritage Thesaurus (, published by The National Monuments Record (NMR)).   When mapping from Merimee  s Thesaurus of Architecture to the AAT and NMR, Boolean operators   AND   and   OR   are used to indicate the equivalence, in addition to the conventional equivalence types (exact and partial).   (See statistics reported in Doerr, 2001 and  


    MSC and DDC 510 schedule, State University of New York in Albany, USA

          Subject coverage: mathematics

          Types of KOS involved: classification schemes

          Languages involved: English

          Status: Research


    A project which maps the American Mathematical Society (AMS) Mathematics Subject Classification (MSC) to the DDC 20 edition Schedule 510 (mathematics) was conducted at the State University of New York in Albany, New York     The mapping rules included: exact matches, specific to general, general to specific, many to one, cyclic mapping, no matches, and specific and broad class mapping.   These mapping strategies are examined in an object-oriented, frame-based analysis for implementation in the expert system shell software (Iyer and Giguere, 1995).


    Polish Project, Poland

          Subject coverage: general

          Types of KOS involved: classification scheme, subject heading list, thesaurus

          Languages involved: English, Polish

    Status: research


    At the Institute for Scientific, Technical and Economic Information (ISTEI) in Warsaw (Poland), a project was conducted in 1992-93 for the establishment of concordances for four controlled vocabularies: Polish Thematic Classification (PTC), descriptors based on the Thesaurus of Common Topics (TCT), Universal Decimal Classification (UDC), and Subject-Heading Language (SHL) of the National Library in Warsaw.   The PTC was chosen as the master language whereas the three others served as target languages (Scibor and Tomasik-Beck, 1994).


    Renardus, Europe   

          Subject coverage: general

          Types of KOS involved: classification scheme

          Languages involved: multilingual


          Status: operational, research


    Renardus is an EU project (coordinated by the National Library of the Netherlands with partners from Denmark, Finland, Germany, the Netherlands, Sweden, and the UK) with the purpose of producing a cross-browsing feature based on the Dewey Decimal Classification (DDC) and improved subject searching across distributed and heterogeneous European subject gateways. The initial investigation included the use of classification systems by Renardus partners   gateways, general mapping approaches and issues, the definition of mapping relationships, and information on technical solutions and the mapping tool.   The approach adopted by the project is a harmonization process that maps local class schemes to a common scheme, thereby enabling users to browse a single subject hierarchy. DDC was chosen as the switching language and common browsing structure.

                      Each DDC class in Renardus presents links to "related collections" which enable the user to jump to the mapped classes in the participating local gateways and to continue browsing in the local classification structure there.   In addition, a virtual browsing feature allows the merging of all local related records from all mapped classes into one common Renardus result set   (Koch, Neuroth , and Day, 2003).


    SAB and DDC, Sweden

          Subject coverage:   general

          Types of KOS involved: classification schemes

          Languages involved: Swedish, English

          Status: operational


    In Sweden, a concordance between Klassifikationssystem f  r svenska bibliotek (SAB) 7th edition, the classification system used by the Royal Library as well as most university libraries and all public libraries, and DDC 21 was presented in year 2000 in the format of a booklet and an online database (IFLA, 2001:34).


    UC Berkeley DARPA Unfamiliar Metadata Project, USA
          Subject coverage: science, engineering

          Types of KOS involved: classification scheme, thesaurus, subject heading list

    Languages involved: English, French, German, Russian, Spanish


          Status: prototype, research


    The project "Mapping Entry Vocabulary to Unfamiliar Metadata Vocabularies" was conducted at the University of California, Berkeley in recent years.   As stated in the project website, the researchers plan to develop Entry Vocabulary Indexes that accept topical statements in the searcher's terms ("Query vocabularies") and respond with a ranked list of terms in the system's vocabulary ("Entry vocabularies"). The prototype Entry Vocabulary Modules included English language indexes to BIOSIS Concept Codes, INSPEC Thesaurus, U.S. Patent and Trademark Office Patent Classification, and the Standard Industrial Classification (SIC) codes, and a multilingual index (supporting queries in English, French, German, Russian, or Spanish) to the physical sciences sections of the Library of Congress Classification (LCC).   When the Entry Vocabulary Module leads users to a promising term in the target metadata vocabulary, a search can be executed using the newly-found metadata against a remote database (Buckland et al., 1999).


    UMLS Metathesaurus, National Library of Medicine, USA          

          Subject coverage: medicine, health, biomedicine, and related areas

    Types of KOS involved: thesaurus, subject heading list, classification scheme,

         coding system, list of controlled terms

    Languages involved: multiple languages


    Status: operational


    UMLS (Unified Medical Language System), led by the National Library of Medicine in the United States, is probably the most ambitious project in harmonizing different vocabularies.   It consists of three "UMLS Knowledge Sources" in which a Metathesaurus is the core source, the other two being the SPECIALIST lexicon and the UMLS Semantic Network.   The UMLS Metathesaurus is a database containing semantic information about biomedical concepts, their various names, and the relationships among them.   It is built from over 100 biomedical source vocabularies, some in multiple languages.   These include thesauri, classification systems, coding systems, and lists of controlled terms that have been developed and are maintained by many different organizations.     The 2003 edition of the Metathesaurus includes 875,255 concepts and 2.14 million concept names (NLM, 2001, 2003).   For mapping index terms from different thesauri, UMLS uses a device called Semantic Network, which, through its 134 semantic types, provides a consistent categorization of all concepts represented in the UMLS Metathesaurus.     The semantic types are the nodes in the Network, and the relationships between them are the links. There are major groupings of semantic types for organisms, anatomical structures, biologic function, chemicals, events, physical objects, and concepts or ideas. The current scope of the UMLS semantic types is broad, allowing for the semantic categorization of a wide range of terminology in multiple domains.   The primary link is the `isa' link. This establishes the hierarchy of types within the Network and is used for deciding on the most specific semantic type available for assignment to a Metathesaurus concept   (NLM, 2003).


    WebDewey, OCLC, USA
    Subject coverage: general

          Types of KOS involved: subject heading list, classification scheme

    Languages involved: English

          Status: operational


    In WebDewey, produced by OCLC, DDC numbers are linked to assigned LC subject headings in MARC records intellectually or statistically where feasible.   Such linking facilitates particularly the subject cataloging and classification process by requiring only the identification of either the appropriate class number or subject heading(s) for each document.   These links, however, do not appear in LCSH (WebDewey website, 2002).



    ADL Homepage. Alexandria Digital Library Project. University of California, Santa Barbara. Available: (Last accessed February 15, 2003.)


    ALA (American Library Association). (2000).   Committee on Cataloging: Description and Access (CC:DA) Task Force on Metadata. Final Report. Available: (Last accessed February 15, 2003.)


    ANSI/NISO (American National Standards Institute/National Information Standards Organization). (1993). Z39.19 - 1993 Guidelines for the Construction, Format, and Management of Monolingual Thesauri. Bethesda, MD: National Information Standards Organization.

    Buckland, M., et al. (1999). Mapping entry vocabulary to unfamiliar metadata vocabularies, D-Lib Magazine, 5(1).   Available: (Last accessed February 15, 2003.)

    CARMEN. WP12. (2000). Cross concordances of classifications and thesauri.   Available: (Last accessed February 15, 2003.)
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    Chan, L. M., Childress, E.,   Dean, R., O'neill, E.T., & Vizine-Goetz, D.   (2001).   A Faceted Approach to Subject Data in The Dublin Core Metadata Record, Journal Of Internet Cataloging 4(1/2):35-47.


    Chemical titles.   (1960 --). Columbus, Ohio: American Chemical Society. ISSN 0009-2711


    Classification Web website (2002). Available: (Last accessed February 15, 2003.)

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