Network Working Group                                           S. Weibel
Request for Comments: 2413      OCLC Online Computer Library Center, Inc.
Category: Informational                                          J. Kunze
                                 University of California, San Francisco
                                                               C. Lagoze
                                                      Cornell University
                                                                 M. Wolf
                                                         Reuters Limited
                                                          September 1998


             Dublin Core Metadata for Resource Discovery

1. Status of this Memo

  This memo provides information for the Internet community.  It does
  not specify an Internet standard of any kind.  Distribution of this
  memo is unlimited.

Copyright Notice

  Copyright (C) The Internet Society (1998).  All Rights Reserved.

2. Abstract

  The Dublin Core Metadata Workshop Series began in 1995 with an
  invitational workshop which brought together librarians, digital
  library researchers, content experts, and text-markup experts to
  promote better discovery standards for electronic resources.  The
  Dublin Core is a 15-element set of descriptors that has emerged from
  this effort in interdisciplinary and international consensus
  building.  This is the first of a set of Informational RFCs
  describing the Dublin Core.  Its purpose is to introduce the Dublin
  Core and to describe the consensus reached on the semantics of each
  of the 15 elements.

3. Introduction

  Finding relevant information on the World Wide Web has become
  increasingly problematic due to the explosive growth of networked
  resources.  Current Web indexing evolved rapidly to fill the demand
  for resource discovery tools, but that indexing, while useful, is a
  poor substitute for richer varieties of resource description.

  An invitational workshop held in March of 1995 brought together
  librarians, digital library researchers, and text-markup specialists
  to address the problem of resource discovery for networked resources.




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  This activity evolved into a series of related workshops and
  ancillary activities that have become known collectively as the
  Dublin Core Metadata Workshop Series.

  The goals that motivate the Dublin Core effort are:

      - Simplicity of creation and maintenance
      - Commonly understood semantics
      - Conformance to existing and emerging standards
      - International scope and applicability
      - Extensibility
      - Interoperability among collections and indexing systems

  These requirements work at cross purposes to some degree, but all are
  desirable goals.  Much of the effort of the Workshop Series has been
  directed at minimizing the tensions among these goals.

  One of the primary deliverables of this effort is a set of elements
  that are judged by the collective participants of these workshops to
  be the core elements for cross-disciplinary resource discovery.  The
  term "Dublin Core" applies to this core of descriptive elements.

  Early experience with Dublin Core deployment has made clear the need
  to support qualification of elements for some applications.  Thus, a
  Dublin Core element may be expressed without qualification (as
  described in this RFC) or with qualifiers that refine its semantics
  (the subject of future RFCs).  For the sake of interoperability,
  simple indexing and discovery tools should be able to ignore any
  qualifiers provided, while more advanced, semantically richer tools
  should be able to use qualifiers to support more specialized or
  precise discovery.

  The broad agreements about syntax and semantics that have emerged
  from the workshop series will be expressed in a series of
  Informational RFCs, of which this document is the first.

4. Description of Dublin Core Elements

  The following is the reference definition of the Dublin Core Metadata
  Element Set.  Further information about the Dublin Core Metadata
  Element Set is available at [1]:

      http://purl.org/metadata/dublin_core

  In the element descriptions below, each element has a descriptive
  name intended to convey a common semantic understanding of the
  element, as well as a formal single-word label intended to make the
  syntactic specification of elements simpler for encoding schemes.



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  Although some environments, such as HTML, are not case-sensitive, it
  is recommended best practice always to adhere to the case conventions
  in the element labels given below to avoid conflicts in the event
  that the metadata is subsequently extracted or converted to a case-
  sensitive environment, such as XML (Extensible Markup Language) [2].

  Each element is optional and repeatable.  Metadata elements may
  appear in any order.  The ordering of multiple occurrences of the
  same element (e.g., Creator) may have a significance intended by the
  provider, but ordering is not guaranteed to be preserved in every
  system.

  To promote global interoperability, a number of the element
  descriptions suggest a controlled vocabulary for the respective
  element values.  It is assumed that other controlled vocabularies
  will be developed for interoperability within certain local domains.

  The metadata elements fall into three groups which roughly indicate
  the class or scope of information stored in them: (1) elements
  related mainly to the Content of the resource, (2) elements related
  mainly to the resource when viewed as Intellectual Property, and (3)
  elements related mainly to the Instantiation of the resource.

       Content          Intellectual Property       Instantiation
       -----------      ---------------------       -------------
       Title                 Creator                  Date
       Subject               Publisher                Format
       Description           Contributor              Identifier
       Type                  Rights                   Language
       Source
       Relation
       Coverage

4.1.  Title                             Label: "Title"

  The name given to the resource, usually by the Creator or Publisher.

4.2.  Author or Creator                 Label: "Creator"

  The person or organization primarily responsible for creating the
  intellectual content of the resource.  For example, authors in the
  case of written documents, artists, photographers, or illustrators in
  the case of visual resources.








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4.3.  Subject and Keywords              Label: "Subject"

  The topic of the resource.  Typically, subject will be expressed as
  keywords or phrases that describe the subject or content of the
  resource.  The use of controlled vocabularies and formal
  classification schemes is encouraged.

4.4.  Description                       Label: "Description"

  A textual description of the content of the resource, including
  abstracts in the case of document-like objects or content
  descriptions in the case of visual resources.

4.5.  Publisher                         Label: "Publisher"

  The entity responsible for making the resource available in its
  present form, such as a publishing house, a university department, or
  a corporate entity.

4.6.  Other Contributor                 Label: "Contributor"

  A person or organization not specified in a Creator element who has
  made significant intellectual contributions to the resource but whose
  contribution is secondary to any person or organization specified in
  a Creator element (for example, editor, transcriber, and
  illustrator).

4.7.  Date                              Label: "Date"

  A date associated with the creation or availability of the resource.
  Recommended best practice is defined in a profile of ISO 8601 [3]
  that includes (among others) dates of the forms YYYY and YYYY-MM-DD.
  In this scheme, for example, the date 1994-11-05 corresponds to
  November 5, 1994.

4.8.  Resource Type                     Label: "Type"

  The category of the resource, such as home page, novel, poem, working
  paper, technical report, essay, dictionary.  For the sake of
  interoperability, Type should be selected from an enumerated list
  that is currently under development in the workshop series.

4.9.  Format                            Label: "Format"

  The data format and, optionally, dimensions (e.g., size, duration) of
  the resource.  The format is used to identify the software and
  possibly hardware that might be needed to display or operate the




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  resource.  For the sake of interoperability, the format should be
  selected from an enumerated list that is currently under development
  in the workshop series.

4.10. Resource Identifier               Label: "Identifier"

  A string or number used to uniquely identify the resource.  Examples
  for networked resources include URLs and URNs (when implemented).
  Other globally-unique identifiers, such as International Standard
  Book Numbers (ISBN) or other formal names are also candidates for
  this element.

4.11. Source                            Label: "Source"

  Information about a second resource from which the present resource
  is derived.  While it is generally recommended that elements contain
  information about the present resource only, this element may contain
  metadata for the second resource when it is considered important for
  discovery of the present resource.

4.12. Language                          Label: "Language"

  The language of the intellectual content of the resource.
  Recommended best practice is defined in RFC 1766 [4].

4.13. Relation                          Label: "Relation"

  An identifier of a second resource and its relationship to the
  present resource.  This element is used to express linkages among
  related resources.  For the sake of interoperability, relationships
  should be selected from an enumerated list that is currently under
  development in the workshop series.

4.14. Coverage                          Label: "Coverage"

  The spatial or temporal characteristics of the intellectual content
  of the resource.  Spatial coverage refers to a physical region (e.g.,
  celestial sector) using place names or coordinates (e.g., longitude
  and latitude).  Temporal coverage refers to what the resource is
  about rather than when it was created or made available (the latter
  belonging in the Date element).  Temporal coverage is typically
  specified using named time periods (e.g., neolithic) or the same
  date/time format [3] as recommended for the Date element.








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4.15. Rights Management                 Label: "Rights"

  A rights management statement, an identifier that links to a rights
  management statement, or an identifier that links to a service
  providing information about rights management for the resource.

5. Security Considerations

  The Dublin Core element set poses no risk to computers and networks.
  It poses minimal risk to searchers who obtain incorrect or private
  information due to careless mapping from rich data descriptions to
  the simple Dublin Core scheme.  No other security concerns are likely
  to be raised by the element description consensus documented here.

6. References

  [1] Further information about the Dublin Core Metadata Element Set,
      http://purl.org/metadata/dublin_core

  [2] Extensible Markup Language (XML), http://www.w3.org/TR/REC-xml

  [3] Date and Time Formats (based on ISO 8601), W3C Technical Note,
      http://www.w3.org/TR/NOTE-datetime

  [4] Alvestrand, H., "Tags for the Identification of Languages", RFC
      1766, March 1995.

7. Authors' Addresses

  Stuart L. Weibel
  OCLC Online Computer Library Center, Inc.
  Office of Research
  6565 Frantz Rd.
  Dublin, Ohio, 43017, USA

  Phone: +1 614-764-6081
  Fax:   +1 614-764-2344
  EMail: [email protected]













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  John A. Kunze
  Center for Knowledge Management
  University of California, San Francisco
  530 Parnassus Ave, Box 0840
  San Francisco, CA  94143-0840, USA

  Phone: +1 510-525-8575
  Fax:   +1 415-476-4653
  EMail: [email protected]


  Carl Lagoze
  University Library and Department of Computer Science
  Cornell University
  Ithaca, NY  14853, USA

  Phone: +1 607-255-6046
  Fax:   +1 607-255-4428
  EMail: [email protected]


  Misha Wolf
  Reuters Limited
  85 Fleet Street
  London EC4P 4AJ, UK

  Phone: +44 171-542-6722
  Fax:   +44 171-542-8314
  EMail: [email protected]






















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8.  Full Copyright Statement

  Copyright (C) The Internet Society (1998).  All Rights Reserved.

  This document and translations of it may be copied and furnished to
  others, and derivative works that comment on or otherwise explain it
  or assist in its implementation may be prepared, copied, published
  and distributed, in whole or in part, without restriction of any
  kind, provided that the above copyright notice and this paragraph are
  included on all such copies and derivative works.  However, this
  document itself may not be modified in any way, such as by removing
  the copyright notice or references to the Internet Society or other
  Internet organizations, except as needed for the purpose of
  developing Internet standards in which case the procedures for
  copyrights defined in the Internet Standards process must be
  followed, or as required to translate it into languages other than
  English.

  The limited permissions granted above are perpetual and will not be
  revoked by the Internet Society or its successors or assigns.

  This document and the information contained herein is provided on an
  "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
  TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
  BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
  HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
  MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
























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