Internet-Draft: draft-kunze-rfc2413bis-01.txt J. Kunze
Dublin Core Metadata University of California
Expires 15 October 2002 15 April 2002
The Dublin Core Metadata Element Set
(http://www.ietf.org/internet-drafts/draft-kunze-rfc2413bis-01.txt)
Status of this Document
This document is an Internet-Draft and is in full conformance with
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1. Abstract
Defines fifteen metadata elements for resource description in a
cross-disciplinary information environment:
Title Contributor Source
Creator Date Language
Subject Type Relation
Description Format Coverage
Publisher Identifier Rights
This document contains the same text as ANSI/NISO Z39.85-2001. It
differs from that standard only where formatting requirements of the
present publishing medium require it. This document supersedes
Internet RFC 2413, which was the first published version of the
Dublin Core.
J. Kunze 1. Abstract [Page 1]
Internet Draft Dublin Core Metadata April 2002
2. Foreword
(This foreword is not part of the standard. It is included for
information only.)
The Dublin Core Metadata Initiative (DCMI) began in 1995 with an
invitational workshop in Dublin, Ohio that brought together
librarians, digital library researchers, content providers, and
text-markup experts to improve discovery standards for information
resources. The original Dublin Core emerged as a small set of
descriptors that quickly drew global interest from a wide variety of
information providers in the arts, sciences, education, business, and
government sectors.
Since the original workshop there has been steadily growing interest
in resource descriptions that are easy to create and that almost
anyone can understand. The potential to increase visibility of
resources in a collection across sectors and subject domains, and to
do so at low cost, is broadly appealing. Services needing
semantically rich descriptions would continue to provide them, but
would attract cross-disciplinary discovery by also providing
universally understandable descriptions common across disciplines.
The digital tourist metaphor is apt. Internet travelers seeking
information in foreign disciplines can use the Dublin Core's
constrained vocabulary to obtain basic guidance in a language that
they understand. Full accessibility to the culture and its services
still requires mastery of the local vocabulary and environment, but a
set of simple facts inscribed in Dublin Core can bring to the
tourist's attention a foreign information portal that might otherwise
have escaped notice.
The interest in cross-domain discovery fueled growing participation
in a series of subsequent DCMI workshops. The Dublin Core metadata
element set described here is a set of 15 descriptors that resulted
from this effort in interdisciplinary and international consensus
building. As of June 2000 the Dublin Core exists in over 20
translations, has been adopted by CEN/ISSS (European Committee for
Standardization / Information Society Standardization System), and is
documented in two internet RFCs (Requests for Comments). It also has
official standing within the WWW Consortium and the Z39.50 standard.
Dublin Core metadata is endorsed formally by governments in three
countries for promoting discovery of government information in
electronic form, and Dublin Core is under consideration as a national
information standard in at least five others.
The Dublin Core is not intended to displace any other metadata
standard. Rather it is intended to co-exist -- often in the same
resource description -- with metadata standards that offer other
semantics. It is fully expected that descriptive records will
contain a mix of elements drawn from various metadata standards, both
simple and complex. Examples of this kind of mixing and of HTML
J. Kunze 2. Foreword [Page 2]
Internet Draft Dublin Core Metadata April 2002
encoding of Dublin Core in general are given in RFC 2731 [RFC2731].
The simplicity of Dublin Core can be both a strength and a weakness.
Simplicity lowers the cost of creating metadata and promotes
interoperability. On the other hand, simplicity does not accommodate
the semantic and functional richness supported by complex metadata
schemes. In effect, the Dublin Core element set trades richness for
wide visibility. The design of Dublin Core mitigates this loss by
encouraging the use of richer metadata schemes in combination with
Dublin Core. Richer schemes can also be mapped to Dublin Core for
export or for cross-system searching. Conversely, simple Dublin Core
records can be used as a starting point for the creation of more
complex descriptions.
3. Scope and Purpose
The Dublin Core metadata element set is a standard for cross-domain
information resource description. Here an information resource is
defined to be anything that has identity; this is the definition used
in Internet RFC 2396, "Uniform Resource Identifiers (URI): Generic
Syntax", by Tim Berners-Lee et al. For Dublin Core applications a
resource will typically be an electronic document.
This standard is for the element set only, which is generally used in
the context of a specific project or application. Local or community
based requirements and policies may impose additional restrictions,
rules, and interpretations. It is not the purpose of this standard
to define the detailed criteria by which the element set will be used
with specific projects and applications.
This standard supersedes Internet RFC 2413, which was the first
published version of the Dublin Core.
4. Definitions
DCMI -- Dublin Core Metadata Initiative, the maintenance agency for
the Dublin Core.
Information resource -- anything that has identity (the same
definition as in Internet RFC 2396).
Lifecycle of an information resource -- a sequence of events that
mark the development and use of an information resource. Some
examples of events in a lifecycle are: Conception of an invention,
Creation of a draft, Revision of an article, Publication of a book,
Acquisition by a library, Transcription to magnetic disk, Migration
to optical storage, Translation into English, and Derivation of a new
work (e.g., a movie).
J. Kunze 4. Definitions [Page 3]
Internet Draft Dublin Core Metadata April 2002
5. The Element Set
In the element descriptions below, each element has a descriptive
label intended to convey a common semantic understanding of the
element, as well as a unique, machine-understandable, single-word
name intended to make the syntactic specification of elements simpler
for encoding schemes.
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 names 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)
[XML].
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.
6. The Elements
Element Name: Title
Label: Title
Definition: A name given to the resource.
Comment: Typically, Title will be a name by which the resource is
formally known.
Element Name: Creator
Label: Creator
Definition: An entity primarily responsible for making the content
of the resource.
Comment: Examples of Creator include a person, an organization,
or a service. Typically, the name of a Creator should
be used to indicate the entity.
Element Name: Subject
Label: Subject and Keywords
Definition: A topic of the content of the resource.
Comment: Typically, Subject will be expressed as keywords, key
phrases, or classification codes that describe a topic
of the resource. Recommended best practice is to select
J. Kunze 6. The Elements [Page 4]
Internet Draft Dublin Core Metadata April 2002
a value from a controlled vocabulary or formal
classification scheme.
Element Name: Description
Label: Description
Definition: An account of the content of the resource.
Comment: Examples of Description include, but are not limited to,
an abstract, table of contents, reference to a graphical
representation of content, or free-text account of the
content.
Element Name: Publisher
Label: Publisher
Definition: An entity responsible for making the resource available.
Comment: Examples of Publisher include a person, an organization,
or a service. Typically, the name of a Publisher should
be used to indicate the entity.
Element Name: Contributor
Label: Contributor
Definition: An entity responsible for making contributions to the
content of the resource.
Comment: Examples of Contributor include a person, an
organization, or a service. Typically, the name of a
Contributor should be used to indicate the entity.
Element Name: Date
Label: Date
Definition: A date of an event in the lifecycle of the resource.
Comment: Typically, Date will be associated with the creation
or availability of the resource. Recommended best
practice for encoding the date value is defined in a
profile of ISO 8601 [W3CDTF] and includes (among others)
dates of the form YYYY-MM-DD.
Element Name: Type
Label: Resource Type
Definition: The nature or genre of the content of the resource.
Comment: Type includes terms describing general categories,
functions, genres, or aggregation levels for content.
Recommended best practice is to select a value from a
controlled vocabulary (for example, the DCMI Type
Vocabulary [DCT]). To describe the physical or digital
manifestation of the resource, use the Format element.
J. Kunze 6. The Elements [Page 5]
Internet Draft Dublin Core Metadata April 2002
Element Name: Format
Label: Format
Definition: The physical or digital manifestation of the resource.
Comment: Typically, Format will include the media-type or
dimensions of the resource. Format may be used to
identify the software, hardware, or other equipment
needed to display or operate the resource. Examples of
dimensions include size and duration. Recommended best
practice is to select a value from a controlled
vocabulary (for example, the list of Internet Media
Types [MIME] defining computer media formats).
Element Name: Identifier
Label: Resource Identifier
Definition: An unambiguous reference to the resource within a given
context.
Comment: Recommended best practice is to identify the resource
by means of a string or number conforming to a formal
identification system. Formal identification systems
include but are not limited to the Uniform Resource
Identifier (URI) (including the Uniform Resource Locator
(URL)), the Digital Object Identifier (DOI), and the
International Standard Book Number (ISBN).
Element Name: Source
Label: Source
Definition: A reference to a resource from which the present
resource is derived.
Comment: The present resource may be derived from the Source
resource in whole or in part. Recommended best practice
is to identify the referenced resource by means of a
string or number conforming to a formal identification
system.
Element Name: Language
Label: Language
Definition: A language of the intellectual content of the resource.
Comment: Recommended best practice is to use RFC 3066 [RFC3066],
which, in conjunction with ISO 639 [ISO639], defines
two- and three-letter primary language tags with
optional subtags. Examples include "en" or "eng" for
English, "akk" for Akkadian, and "en-GB" for English
used in the United Kingdom.
J. Kunze 6. The Elements [Page 6]
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Element Name: Relation
Label: Relation
Definition: A reference to a related resource.
Comment: Recommended best practice is to identify the referenced
resource by means of a string or number conforming to a
formal identification system.
Element Name: Coverage
Label: Coverage
Definition: The extent or scope of the content of the resource.
Comment: Typically, Coverage will include spatial location (a
place name or geographic coordinates), temporal period
(a period label, date, or date range), or jurisdiction
(such as a named administrative entity). Recommended
best practice is to select a value from a controlled
vocabulary (for example, the Thesaurus of Geographic
Names [TGN]) and to use, where appropriate, named places
or time periods in preference to numeric identifiers
such as sets of coordinates or date ranges.
Element Name: Rights
Label: Rights Management
Definition: Information about rights held in and over the resource.
Comment: Typically, Rights will contain a rights management
statement for the resource, or reference a service
providing such information. Rights information often
encompasses Intellectual Property Rights (IPR),
Copyright, and various Property Rights. If the Rights
element is absent, no assumptions may be made about any
rights held in or over the resource.
7. 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
8. Author's Address
John A. Kunze
Center for Knowledge Management
University of California, San Francisco
530 Parnassus Ave, Box 0840
San Francisco, CA 94143-0840, USA
Fax: +1 415-476-4653
EMail: jak@ckm.ucsf.edu
J. Kunze 8. Author's Address [Page 7]
Internet Draft Dublin Core Metadata April 2002
9. References
[DCT] DCMI Type Vocabulary. DCMI Recommendation, 11 July 2000.
http://dublincore.org/documents/dcmi-type-vocabulary/
[ISO3166] ISO 3166 - Codes for the representation of names of
countries. http://www.din.de/gremien/nas/nabd/iso3166ma/
[ISO639] ISO 639-2 - Codes for the representation of names of
languages, Alpha-3 code (ISO 639-2:1998).
http://www.loc.gov/standards/iso639-2/langhome.html
[MIME] Internet Media Types. http://www.isi.edu/in-
notes/iana/assignments/media-types/media-types
[RFC3066] Tags for the Identification of Languages, Internet RFC
3066. http://www.ietf.org/rfc/rfc3066.txt
[RFC2396] Uniform Resource Identifiers (URI): Generic Syntax,
Internet RFC 2396. http://www.ietf.org/rfc/rfc2396.txt
[RFC2413] Dublin Core Metadata for Resource Discovery. Internet RFC
2413. http://www.ietf.org/rfc/rfc2413.txt
[RFC2731] Encoding Dublin Core Metadata in HTML. Internet RFC 2731.
http://www.ietf.org/rfc/rfc2731.txt
[TGN] Getty Thesaurus of Geographic Names.
http://www.getty.edu/research/tools/vocabulary/tgn/index.html
[W3CDTF] Date and Time Formats, W3C Note.
http://www.w3.org/TR/NOTE-datetime
[XML] Extensible Markup Language. http://www.w3.org/TR/REC-xml
10. Appendix A: Further Reading
(This appendix is not part of the standard. It is included for
information only.)
Further information about the Dublin Core metadata element set is
available at the URL,
http://dublincore.org/
This web site contains information about workshops, reports, working
group papers, projects, and new developments concerning the Dublin
Core Metadata Initiative (DCMI).
J. Kunze 10. Appendix A: Further Reading [Page 8]
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11. Appendix B: Maintenance Agency
(This appendix is not part of the standard. It is included for
information only.)
The Dublin Core Metadata Initiative (DCMI) is responsible for the
development, standardization and promotion of the Dublin Core
metadata element set. Information on DCMI is available at the URL,
http://dublincore.org/
12. Copyright Notice
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J. Kunze 12. Copyright Notice [Page 9]