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Date: Tue, 09 Apr 2002 09:41:01 GMT Server: Apache/1.3.20 (Unix) Last-Modified: Mon, 27 Apr 1998 14:28:00 GMT ETag: "304e79-3745-354495f0" Accept-Ranges: bytes Content-Length: 14149 Connection: close Content-Type: text/plain Dublin Core Workshop Series Network Working Group S. WeibelInternet-DraftRequest for Comments: 2413 OCLC Online Computer Library Center, Inc. Category: Informational J. Kunzedraft-kunze-dc-02.txtUniversity of California, San Francisco C. Lagoze10 FebruaryCornell University M. Wolf Reuters Limited September 1998Expires in six monthsDublin Core Metadata forSimpleResource Discovery 1. Status of thisDocumentMemo Thisdocument ismemo provides information for the Internet community. It does not specify anInternet-Draft. Internet-Drafts are working documentsInternet standard oftheany kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The InternetEngineering Task Force (IETF), its areas,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, andits working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents validtext-markup experts to promote better discovery standards for electronic resources. The Dublin Core is amaximum15-element set ofsix monthsdescriptors that has emerged from this effort in interdisciplinary andmay be updated, replaced, or obsoleted by other documents at any time. Itinternational consensus building. This isinappropriate to use Internet-Drafts as reference material or to cite them other than as ``work in progress.'' To learnthecurrent statusfirst ofany Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast). Distributiona set ofthis documentInformational RFCs describing the Dublin Core. Its purpose isunlimited. Please send commentstoweibel@oclc.org, orintroduce the Dublin Core and to describe thediscussion list meta2@mrrl.lut.ac.uk. 2.consensus reached on the semantics of each of the 15 elements. 3. Introduction Finding relevant information on the World Wide Web has become increasingly problematicin proportiondue 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''"Dublin Core" applies to this core of descriptive elements. Early experience with Dublin Core deployment has made clear the need to supportadditionalqualification of elements for some applications. Thus, a Dublin Coreelementselement may be expressed without qualification (as described insimple unqualified ways that minimal discovery and retrieval tools can use,this RFC) orthey may be expressedwithadditional structure to support semantics-sharpeningqualifiers thatminimalrefine its semantics (the subject of future RFCs). For the sake of interoperability, simple indexing and discovery toolscan safelyshould be able to ignorebut thatany qualifiers provided, while morecomplexadvanced, semantically richer toolscan employshould be able toincrease discovery precision.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 offiveInformational RFCs, of which this document is the first.These RFCs (currently they are Internet-Drafts) will comprise the following documents. 2.1. Dublin Core Metadata for Simple Resource Discovery An introduction to the4. Description of Dublin Coreand a description ofElements The following is thesemanticsreference definition of the15-elementDublin Coreelement set without qualifiers. This is the present document. 2.2. Encoding Dublin Core Metadata in HTML A formal description of the convention for embedding unqualified Dublin Core metadata in an HTML file. 2.3. Qualified Dublin Core Metadata for Simple Resource Discovery The principles of element qualification and the semantics of Dublin Core metadata when expressed with a recommended qualifier set known as the Canberra Qualifiers. 2.4. Encoding Qualified Dublin Core Metadata in HTML A formal description of the convention for embedding qualified Dublin Core metadata in an HTML file. 2.5. Dublin Core on the Web: RDF Compliance and DC Extensions A formal description for encoding Dublin Core metadata with qualifiers in RDF (Resource Description Framework) [1] compliant metadata, and how to extend the core element set. 3. Description of Dublin Core Elements The following is the reference definition ofMetadata Element Set. Further information about the Dublin Core Metadata ElementSet. The evolving reference description, including any defined qualifiers, residesSet is available at[2]:[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 acase-sensitivecase- sensitive environment, such as XML (Extensible Markup Language)[3].[2]. Each element is optional and repeatable.Furthermore, metadataMetadata elements may appear in anyorder, and with noorder. The ordering of multiple occurrences of the same element (e.g., Creator) may have a significancebeing attachedintended by the provider, but ordering is not guaranteed tothat order.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.A metadata element's meaning is unaffected by whether or not the element is embedded in the resource that it describes.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 PublisherTypeFormat Description ContributorFormat Source RightsIdentifier Type Rights Language Source Relation Coverage3.1.4.1. Title Label: "Title" The name given to the resource, usually by the Creator or Publisher.3.2.4.2. 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.3.3.Weibel, et. al. Informational [Page 3] RFC 2413 Dublin Core Metadata for Resource Discovery September 1998 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.3.4.4.4. 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.3.5.4.5. 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.3.6.4.6. 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).3.7.4.7. Date Label: "Date" A date associated with the creation or availability of the resource.Such a date is not to be confused with one belonging in the Coverage element, which would be associated with the resource only insofar as the intellectual content is somehow about that date.Recommended best practice is defined in a profile of ISO 8601[4][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, 1994.3.8.4.8. 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.3.9.4.9. Format Label: "Format" The data format and, optionally, dimensions (e.g., size, duration) of theresource,resource. The format is used to identify the software and possibly hardware that might be needed to display or operate the Weibel, et. al. Informational [Page 4] RFC 2413 Dublin Core Metadata for Resource Discovery September 1998 resource. For the sake of interoperability,Formatthe format should be selected from an enumerated list that is currently under development in the workshop series.3.10.4.10. 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.3.11.4.11. 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 containa date, creator, format, identifier, or othermetadata for the second resource when it is considered important for discovery of the presentresource; recommendedresource. 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 tousetheRelationpresent resource. This elementinstead. For example, itispossibleused touse a Source date of 1603 in a description of a 1996 film adaptation of a Shakespearean play, but it is preferred instead to use Relation "IsBasedOn" with a reference to a separate resource whose description contains a Date of 1603. Source is not applicable if the present resource is in its original form. 3.12. Language Label: "Language" The language of the intellectual content of the resource. Where practical, the content of this field should coincide with RFC 1766 [5]; examples include en, de, es, fi, fr, ja, th, and zh. 3.13. Relation Label: "Relation" An identifier of a second resource and its relationship to the present resource. This element permits links betweenexpress linkages among relatedresources and resource descriptions to be indicated. Examples include an edition of a work (IsVersionOf), a translation of a work (IsBasedOn), a chapter of a book (IsPartOf), and a mechanical transformation of a dataset into an image (IsFormatOf).resources. For the sake of interoperability, relationships should be selected from an enumerated list that is currently under development in the workshop series.3.14.4.14. Coverage Label: "Coverage" The spatial or temporal characteristics of the intellectual content of the resource. Spatial coverage refers to a physical region (e.g., celestialsector); usesector) using place names or coordinates (e.g., longitude andlatitude) or place names that are from a controlled list or are fully spelled out.latitude). Temporal coverage refers to what the resource is about rather than when it was created or made available (the latter belonging in the Dateelement); useelement). Temporal coverage is typically specified using named time periods (e.g., neolithic) or the same date/time format(often a range) [4][3] as recommended for the Dateelement or time periods that are from a controlled list or are fully spelled out. 3.15.element. Weibel, et. al. Informational [Page 5] RFC 2413 Dublin Core Metadata for Resource Discovery September 1998 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.4.5. 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.5.6. References [1]Resource Description Framework (RDF) Model and Syntax, http://www.w3.org/TR/WD-rdf-syntax [2]Further information about the Dublin Core Metadata ElementSet: Reference Description,Set, http://purl.org/metadata/dublin_core[3][2] Extensible Markup Language (XML),http://www.w3.org/TR/PR-xml [4]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[5] RFC 1766, Tags[4] Alvestrand, H., "Tags for the Identification ofLanguages, http://ds.internic.net/rfc/rfc1766.txt 6.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, USAEmail: weibel@oclc.org Voice:Phone: +1 614-764-6081 Fax: +1 614-764-2344 EMail: weibel@oclc.org Weibel, 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, USAEmail: jak@ckm.ucsf.edu Voice:Phone: +1415-502-6660510-525-8575 Fax: +1 415-476-4653 EMail: jak@ckm.ucsf.edu Carl LagozeDigitalUniversity LibraryResearch Groupand Department of Computer Science Cornell University Ithaca, NY 14853, USAEmail:Phone: +1 607-255-6046 Fax: +1 607-255-4428 EMail: lagoze@cs.cornell.eduVoice: +1-607-255-6046Misha Wolf Reuters Limited 85 Fleet Street London EC4P 4AJ, UK Phone: +44 171-542-6722 Fax:+1-607-255-4428+44 171-542-8314 EMail: misha.wolf@reuters.com Weibel, et. al. Informational [Page 7] RFC 2413 Dublin Core Metadata for Resource Discovery September 1998 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. Weibel, et. al. Informational [Page 8] ----