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Dublin Core

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Logo of DCMI, maintenance agency for Dublin Core Terms

The Dublin Core vocabulary, also known as the Dublin Core Metadata Terms (DCMT), is a general purpose metadata vocabulary for describing resources of any type. It was first developed for describing web content in the early days of the World Wide Web. The Dublin Core Metadata Initiative (DCMI) is responsible for maintaining the Dublin Core vocabulary.

Initially developed as fifteen terms in 1998 the set of elements has grown over time and in 2008 was redefined as an Resource Description Framework (RDF) vocabulary.[1]

Designed with minimal constraints, each Dublin Core element is optional and may be repeated. There is no prescribed order in Dublin Core for presenting or using the elements.

Milestones

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  • 1995 - In 1995 an invitational meeting hosted by the Ohio College Library Center (OCLC) and the National Center for Supercomputing Applications (NCSA) takes place at Dublin, Ohio, the headquarters of OCLC.[2]
  • 1998, September - RFC 2413 "Dublin Core Metadata for Resource Discovery" details the original 15-element vocabulary.[3]
  • 2000 - Issuance of Qualified Dublin Core.
  • 2001 - Publication of the Dublin Core Metadata Element Set as ANSI/NISO Z39.85.[4]
  • 2008 - Publication of Dublin Core Metadata Initiative Terms in RDF.[5][6]

Evolution of the Dublin Core vocabulary

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The Dublin Core Element Set was a response to concern about accurate finding of resources on the Web, with some early assumptions that this would be a library function. In particular it anticipated a future in which scholarly materials would be searchable on the World Wide Web. Whereas HTML was being used to mark-up the structure of documents, metadata was needed to mark-up the contents of documents. Given the great number of documents on, and soon to be on, the World Wide Web, it was proposed that "self-identifying" documents would be necessary.[7][8]

To this end, the Dublin Core Metadata Workshop met beginning in 1995 to develop a vocabulary that could be used to insert consistent metadata into Web documents.[9] Originally defined as 15 metadata elements, the Dublin Core Element Set allowed authors of web pages a vocabulary and method for creating simple metadata for their works.[10] It provided a simple, flat element set that could be used

Qualified Dublin Core was developed in the late 1990s to provide an extension mechanism to the vocabulary of 15 elements. This was a response to communities whose metadata needs required additional detail.[11]

In 2012, the DCMI Metadata Terms was created using a RDF data model.[12] This expanded element set incorporates the original 15 elements and many of the qualifiers of the qualified Dublin Core as RDF properties.[citation needed] The full set of elements is found under the namespace http://purl.org/dc/terms/. There is a separate namespace for the original 15 elements as previously defined: http://purl.org/dc/elements/1.1/.[13]

Dublin Core Metadata Element Set, 1995

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The Dublin Core vocabulary published in 1999 consisted of 15 terms:

  • contributor
  • coverage
  • creator
  • date
  • description
  • format
  • identifier
  • language
  • publisher
  • relation
  • rights
  • source
  • subject
  • title
  • type

The vocabulary was commonly expressed in HTML 'meta' tagging in the "<head>" section of an HTML-encoded page.[14] 

<head>
   <meta name="DC.title" content="Services to Government" >
   <meta name="DC.date" content="1997-07" >
 </head>

The vocabulary could be used in any metadata serialization including key/value pairs and XML.[15]

Qualified Dublin Core, 2000

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Subsequent to the specification of the original 15 elements, Qualified Dublin Core was developed to provide an extension mechanism to be used when the primary 15 terms were not sufficient. A set of common refinements was provided in the documentation. These schemes include controlled vocabularies and formal notations or parsing rules.[16] Qualified Dublin Core was not limited to these specific refinements, allowing communities to create extended metadata terms to meet their needs.[11]

The guiding principle for the qualification of Dublin Core elements, colloquially known as the Dumb-Down Principle,[17] states that an application that does not understand a specific element refinement term should be able to ignore the qualifier and treat the metadata value as if it were an unqualified (broader) element. While this may result in some loss of specificity, the remaining element value (without the qualifier) should continue to be generally correct and useful for discovery.

Qualified Dublin Core added qualifiers to these elements:

Qualified Dublin Core Elements
Element Qualifier
Title Alternative
Description Table Of Contents
" Abstract
DateCreated Valid
" Available
" Issued
" Modified
FormatExtent Medium
Relation Is Version Of
" Has Version
" Is Replaced By
" Replaces
" Is Required By
" Requires
" Is Part Of
" Has Part
" Is Referenced By
" References
" Is Format Of
" Has Format
Coverage Spatial
" Temporal

And added three elements not in the base 15:

  • Audience
  • Provenance
  • RightsHolder

Qualified Dublin Core is often used with a "dot syntax", with a period separating the element and the qualifier(s). This is shown in this excerpted example provided by Chan and Hodges:[11]

Title: D-Lib Magazine
Title.alternative: Digital Library Magazine
Identifier.ISSN: 1082-9873
Publisher: Corporation for National Research Initiatives
Publisher.place: Reston, VA.
Subject.topical.LCSH: Digital libraries - Periodicals

DCMI Metadata Terms, 2008

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The DCMI Metadata Terms lists the current set of the Dublin Core vocabulary.[12] This set includes the fifteen terms of the DCMES (in italic), as well as many of the qualified terms. Each term has a unique URI in the namespace http://purl.org/dc/terms, and all are defined as RDF properties.

  • abstract
  • accessRights
  • accrualMethod
  • accrualPeriodicity
  • accrualPolicy
  • alternative
  • audience
  • available
  • bibliographicCitation
  • conformsTo
  • contributor
  • coverage
  • created
  • creator
  • date
  • dateAccepted
  • dateCopyrighted
  • dateSubmitted
  • description
  • educationLevel
  • extent
  • format
  • hasFormat
  • hasPart
  • hasVersion
  • identifier
  • instructionalMethod
  • isFormatOf
  • isPartOf
  • isReferencedBy
  • isReplacedBy
  • isRequiredBy
  • issued
  • isVersionOf
  • language
  • license
  • mediator
  • medium
  • modified
  • provenance
  • publisher
  • references
  • relation
  • replaces
  • requires
  • rights
  • rightsHolder
  • source
  • spatial
  • subject
  • tableOfContents
  • temporal
  • title
  • type
  • valid

It also includes these RDF classes which are used as domains and ranges of some properties:

  • Agent
  • AgentClass
  • BibliographicResource
  • FileFormat
  • Frequency
  • Jurisdiction
  • LicenseDocument
  • LinguisticSystem
  • Location
  • LocationPeriod/OrJurisdiction
  • MediaType
  • MediaTypeOrExtent
  • MethodOfAccrual
  • MethodOfInstruction
  • PeriodOfTime
  • PhysicalMedium
  • PhysicalResource
  • Policy
  • ProvenanceStatement
  • RightsStatement
  • SizeOrDuration
  • Standard

Maintenance of the standard

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Changes that are made to the Dublin Core standard are reviewed by a DCMI Usage Board within the context of a DCMI Namespace Policy.[18] This policy describes how terms are assigned and also sets limits on the amount of editorial changes allowed to the labels, definitions, and usage comments.[19]

Dublin Core as standards

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The Dublin Core Metadata Terms vocabulary has been formally standardized internationally as ISO 15836 by the International Organization for Standardization (ISO)[20] and as IETF RFC 5013 by the Internet Engineering Task Force (IETF),[21] as well as in the U.S. as ANSI/NISO Z39.85 by the National Information Standards Organization (NISO).[22]

Syntax

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Syntax choices for metadata expressed with the Dublin Core elements depend on context. Dublin Core concepts and semantics are designed to be syntax independent[clarification needed] and apply to a variety of contexts, as long as the metadata is in a form suitable for interpretation by both machines and people.

Notable applications

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One Document Type Definition based on Dublin Core is the Open Source Metadata Framework (OMF) specification.[23] OMF is in turn used by Rarian (superseding ScrollKeeper), which is used by the GNOME desktop and KDE help browsers and the ScrollServer documentation server.

PBCore is also based on Dublin Core.[24] The Zope CMF's Metadata products, used by the Plone, ERP5, the Nuxeo CPS Content management systems, SimpleDL, and Fedora Commons also implement Dublin Core. The EPUB e-book format uses Dublin Core metadata in the OPF file.[25] Qualified Dublin Core is used in the DSpace archival management software.[26]

The Australian Government Locator Service (AGLS) metadata standard is an application profile of Dublin Core.[27]: 5 

See also

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References

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  1. ^ "Dublin Core". Dublin Core Metadata Initiative. 22 December 2011.
  2. ^ "DCMI: The OCLC/NCSA Metadata Workshop: The Essential Elements of Network Object Description". dublincore.org. March 1995. Retrieved 13 October 2019.
  3. ^ Weibel, S.; Kunze, J.; Lagoze, C.; Wolf, M. (September 1998). "Dublin Core Metadata for Resource Discovery". RFC Editor. Retrieved 3 June 2024.
  4. ^ "ANSI/NISO Z39.85-2001" (PDF). ANSI/NISO. 2001.
  5. ^ Baker, Tom (2012). "Libraries, languages of description, and linked data: a Dublin Core perspective". Library Hi Tech. 30 (1): 116–133. doi:10.1108/07378831211213256. ISSN 0737-8831.
  6. ^ "Expressing Dublin Core Metadata Using RDF". Dublin Core Metadata Initiative. 14 June 2012.
  7. ^ Weibel, S.L. (1995). "The World Wide Web and emerging Internet resource discovery standards for scholarly literature". Library Trends. -43 (4): 627–44.
  8. ^ Weibel, S. (1995). "Metadata: the foundations of resource description". D-Lib Magazine. doi:10.1045/july95-weibel.
  9. ^ Weibel, S.; Lagoze, C. (1997). "An element set to support resource discovery". International Journal of Digital Libraries. 1 (2): 176–186. doi:10.1007/s007990050013.
  10. ^ Greenberg, Jane; Pattuelli, Maria Cristina; Parsia, Bijan; Davenport Robertson, W. (2001). "Author-generated Dublin Core metadata for web resources: a baseline study in an organization In". Proceedings of the International Conference on Dublin Core and Metadata Applications.
  11. ^ a b c Chan, Lois Mai; Hodges, Theodora (2007). Cataloging and classification : an introduction (Third ed.). Scarecrow Press.
  12. ^ a b "DCMI Metadata Terms". Dublincore.org. Retrieved 4 December 2015.
  13. ^ "DCMI: Dublin Core Metadata Element Set, Version 1.1: Reference Description". dublincore.org. Retrieved 3 April 2018.
  14. ^ Kunze, John A. (December 1999). "Encoding Dublin Core Metadata in HTML". IETF.org. Retrieved 17 June 2021.
  15. ^ Johnston, Pete; Powell, Andy (30 May 2006). "Expressing Dublin Core™ metadata using XML".
  16. ^ "Using Dublin Core™ - Dublin Core™ Qualifiers". 2005.
  17. ^ "DCMI: DCMI Grammatical Principles". dublincore.org. Retrieved 3 April 2018.
  18. ^ Powell, Andy; Wagner, Harry (2 July 2007). "Namespace Policy for Dublin Core Metadata Initiative".
  19. ^ "Dublin Core Metadata Element Set, Version 1.1". Dublincore.org. Retrieved 4 December 2015.
  20. ^ "ISO 15836-1:2017 – Information and documentation – The Dublin Core metadata element set – Part 1: Core elements". International Organization for Standardization. May 2017. Retrieved 2 October 2018.
  21. ^ The Dublin Core Metadata Element Set, Dublin Core Metadata Initiative, August 2007
  22. ^ "NISO Standards – National Information Standards Organization". Niso.org. 22 May 2007. Archived from the original on 16 November 2011. Retrieved 5 April 2013.
  23. ^ "m e t a l a b open source metadata framework". ibiblio.org. Retrieved 3 April 2018.
  24. ^ "PBCore Schema – PBCore". pbcore.org. Retrieved 19 January 2018. PBCore is built on the foundation of the Dublin Core (ISO 15836), an international standard for resource discovery.
  25. ^ "Open Packaging Format (OPF) § Publication Metadata". International Digital Publishing Forum. Retrieved 11 November 2017.
  26. ^ "Dspace metadata and bitstream format registries". Dspace Wiki.
  27. ^ "AGLS Metadata Standard Part 1 – Reference Description" (PDF). National Archives of Australia. 30 June 2010. Retrieved 28 November 2019.
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