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Network Working Group                                           S. WeibelRequest 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 1998Dublin Core Metadata for Resource Discovery1. 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.Weibel, et. al.              Informational                      [Page 1]

RFC 2413      Dublin Core Metadata for Resource Discovery September 1998   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.Weibel, et. al.              Informational                      [Page 2]

RFC 2413      Dublin Core Metadata for Resource Discovery September 1998   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        Coverage4.1.  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.Weibel, et. al.              Informational                      [Page 3]

RFC 2413      Dublin Core Metadata for Resource Discovery September 19984.3.  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 theWeibel, et. al.              Informational                      [Page 4]

RFC 2413      Dublin Core Metadata for Resource Discovery September 1998   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 inRFC 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.Weibel, et. al.              Informational                      [Page 5]

RFC 2413      Dublin Core Metadata for Resource Discovery September 19984.15. 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",RFC1766, 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: weibel@oclc.orgWeibel, et. al.              Informational                      [Page 6]

RFC 2413      Dublin Core Metadata for Resource Discovery September 1998   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: jak@ckm.ucsf.edu   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: lagoze@cs.cornell.edu   Misha Wolf   Reuters Limited   85 Fleet Street   London EC4P 4AJ, UK   Phone: +44 171-542-6722   Fax:   +44 171-542-8314   EMail: misha.wolf@reuters.comWeibel, et. al.              Informational                      [Page 7]

RFC 2413      Dublin Core Metadata for Resource Discovery September 19988.  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.Weibel, et. al.              Informational                      [Page 8]