Using Dublin Core in Semantic MediaWiki

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Using Dublin Core


Diane Hillmann

Date Issued: 2005-11-07




Is Replaced By: Not applicable
Latest Version:




Status of Document:

[/documents/#recommendedresources DCMI Recommended Resource]

Description of Document: This document is intended as an entry point for users of Dublin Core. For non-specialists, it will assist them in creating simple descriptive records for information resources (for example, electronic documents). Specialists may find the document a useful point of reference to the documentation of Dublin Core, as it changes and grows.

Table of Contents

[/documents/usageguide/#introduction 1. Introduction]

  • [/documents/usageguide/#whatismetadata 1.1. What is Metadata?]
  • [/documents/usageguide/#whatis 1.2. What is the Dublin Core?]
  • [/documents/usageguide/#purpose 1.3. The Purpose and Scope of This Guide]

[/documents/usageguide/#whichsyntax 2. Syntax, Storage and Maintenance Issues]

  • [/documents/usageguide/#html 2.1. HTML]
  • [/documents/usageguide/#rdfxml 2.2. RDF/XML]
  • [/documents/usageguide/#metadatacontained 2.3. Metadata Storage and Maintenance]

[/documents/usageguide/#basicprinciples 3. Element Content and Controlled Vocabularies]
[/documents/usageguide/elements.shtml 4. The Elements]
[/documents/usageguide/qualifiers.shtml 5. Dublin Core Qualifiers]
[/documents/usageguide/appendix_roles.shtml 6. Appendix, Roles]
[/documents/usageguide/glossary.shtml 7. Glossary]
[/documents/usageguide/bibliography.shtml 8. Bibliography]

1. Introduction

1.1. What is Metadata?

Metadata has been with us since the first librarian made a list of the items on a shelf of handwritten scrolls. The term "meta" comes from a Greek word that denotes "alongside, with, after, next." More recent Latin and English usage would employ "meta" to denote something transcendental, or beyond nature. Metadata, then, can be thought of as data about other data. It is the Internet-age term for information that librarians traditionally have put into catalogs, and it most commonly refers to descriptive information about Web resources.

A metadata record consists of a set of attributes, or elements, necessary to describe the resource in question. For example, a metadata system common in libraries -- the library catalog -- contains a set of metadata records with elements that describe a book or other library item: author, title, date of creation or publication, subject coverage, and the call number specifying location of the item on the shelf.

The linkage between a metadata record and the resource it describes may take one of two forms:

  1. elements may be contained in a record separate from the item, as in the case of the library's catalog record; or
  2. the metadata may be embedded in the resource itself.

Examples of embedded metadata that is carried along with the resource itself include the Cataloging In Publication (CIP) data printed on the verso of a book's title page; or the TEI header in an electronic text. Many metadata standards in use today, including the Dublin Core standard, do not prescribe either type of linkage, leaving the decision to each particular implementation.

Although the concept of metadata predates the Internet and the Web, worldwide interest in metadata standards and practices has exploded with the increase in electronic publishing and digital libraries, and the concomitant "information overload" resulting from vast quantities of undifferentiated digital data available online. Anyone who has attempted to find information online using one of today's popular Web search services has likely experienced the frustration of retrieving hundreds, if not thousands, of "hits" with limited ability to refine or make a more precise search. The wide scale adoption of descriptive standards and practices for electronic resources will improve retrieval of relevant resources in any venue where information retrieval is critical. As noted by Weibel and Lagoze, two leaders in the fields of metadata development and digital libraries:

"The association of standardized descriptive metadata with networked objects has the potential for substantially improving resource discovery capabilities by enabling field-based (e.g., author, title) searches, permitting indexing of non-textual objects, and allowing access to the surrogate content that is distinct from access to the content of the resource itself." (Weibel and Lagoze, 1997)

In the last years we have also seen an increase in the application of Dublin Core metadata in more closed environments. There are implementations where Dublin Core metadata is used to describe resources held, owned or produced by companies, governments and international organisations to supporting portal services or internal knowledge management. There are also implementations where Dublin Core metadata is used as a common exchange format supporting the aggregation of collections of metadata, such as the case of the Open Archive Initiative. In these cases, like in the open environment of the Web, the concept of standardized descriptive metadata provides a powerful mechanism to improve retrieval for specific applications and specific user communities. It is this need for "standardized descriptive metadata" that the Dublin Core addresses.

1.2. What is the Dublin Core?

The Dublin Core metadata standard is a simple yet effective element set for describing a wide range of networked resources. The Dublin Core standard includes two levels: Simple and Qualified. Simple Dublin Core comprises fifteen elements; Qualified Dublin Core includes three additional elements (Audience, Provenance and RightsHolder), as well as a group of element refinements (also called qualifiers) that refine the semantics of the elements in ways that may be useful in resource discovery. The semantics of Dublin Core have been established by an international, cross-disciplinary group of professionals from librarianship, computer science, text encoding, the museum community, and other related fields of scholarship and practice.

Another way to look at Dublin Core is as a "small language for making a particular class of statements about resources". In this language, there are two classes of terms -- elements (nouns) and qualifiers (adjectives) -- which can be arranged into a simple pattern of statements. The resources themselves are the implied subjects in this language. (For additional discussion of Dublin Core Grammar, see [/usage/documents/principles/ "DCMI Grammatical Principles"]) In the diverse world of the Internet, Dublin Core can be seen as a "metadata pidgin for digital tourists": easily grasped, but not necessarily up to the task of expressing complex relationships or concepts.

The Dublin Core basic element set is outlined in [/documents/usageguide/elements.shtml Section 4]. Each element is optional and may be repeated. Most elements also have a limited set of qualifiers or refinements, attributes that may be used to further refine (not extend) the meaning of the element. The Dublin Core Metadata Initiative (DCMI) has established standard ways to refine elements and encourage the use of encoding and vocabulary schemes. The full set of [/documents/dcmi-terms/ elements and element refinements] conforming to DCMI "best practice" is available, with a [/dcregistry/ formal registry] available as well.

Three other Dublin Core principles bear mentioning here, as they are critical to understanding how to think about the relationship of metadata to the underlying resources they describe.

1. The One-to-One Principle. In general Dublin Core metadata describes one manifestation or version of a resource, rather than assuming that manifestations stand in for one another. For instance, a jpeg image of the Mona Lisa has much in common with the original painting, but it is not the same as the painting. As such the digital image should be described as itself, most likely with the creator of the digital image included as a Creator or Contributor, rather than just the painter of the original Mona Lisa. The relationship between the metadata for the original and the reproduction is part of the metadata description, and assists the user in determining whether he or she needs to go to the Louvre for the original, or whether his/her need can be met by a reproduction.

2. The Dumb-down Principle. The qualification of Dublin Core properties is guided by a rule known colloquially as the Dumb-Down Principle. According to this rule, a client should be able to ignore any qualifier and use the value as if it were unqualified. While this may result in some loss of specificity, the remaining element value (minus the qualifier) must continue to be generally correct and useful for discovery. Qualification is therefore supposed only to refine, not extend the semantic scope of a property.

3. Appropriate values. Best practice for a particular element or qualifier may vary by context, but in general an implementor cannot predict that the interpreter of the metadata will always be a machine. This may impose certain constraints on how metadata is constructed, but the requirement of usefulness for discovery should be kept in mind.

Although the Dublin Core was originally developed with an eye to describing document-like objects (because traditional text resources are fairly well understood), DC metadata can be applied to other resources as well. Its suitability for use with particular non-document resources will depend to some extent on how closely their metadata resembles typical document metadata and also what purpose the metadata is intended to serve. (Implementors interested in using Dublin Core for diverse resources are encouraged to browse the [/projects/ Dublin Core Projects pages] for ideas on using Dublin Core metadata for their resources.)

Dublin Core has as its goals:

Simplicity of creation and maintenance

The Dublin Core element set has been kept as small and simple as possible to allow a non-specialist to create simple descriptive records for information resources easily and inexpensively, while providing for effective retrieval of those resources in the networked environment.

Commonly understood semantics

Discovery of information across the vast commons of the Internet is hindered by differences in terminology and descriptive practices from one field of knowledge to the next. The Dublin Core can help the "digital tourist" -- a non-specialist searcher -- find his or her way by supporting a common set of elements, the semantics of which are universally understood and supported. For example, scientists concerned with locating articles by a particular author, and art scholars interested in works by a particular artist, can agree on the importance of a "creator" element. Such convergence on a common, if slightly more generic, element set increases the visibility and accessibility of all resources, both within a given discipline and beyond.

International scope

The Dublin Core Element Set was originally developed in English, but versions are being created in [/resources/translations/ many other languages], including Finnish, Norwegian, Thai, Japanese, French, Portuguese, German, Greek, Indonesian, and Spanish. [/groups/languages/ The DCMI Localization and Internationalization Special Interest Group] is coordinating efforts to link these versions in a distributed registry.

Although the technical challenges of internationalization on the World Wide Web have not been directly addressed by the Dublin Core development community, the involvement of representatives from virtually every continent has ensured that the development of the standard considers the multilingual and multicultural nature of the electronic information universe.


While balancing the needs for simplicity in describing digital resources with the need for precise retrieval, Dublin Core developers have recognized the importance of providing a mechanism for extending the DC element set for additional resource discovery needs. It is expected that other communities of metadata experts will create and administer additional metadata sets, specialized to the needs of their communities. Metadata elements from these sets could be used in conjunction with Dublin Core metadata to meet the need for interoperabilbility. The DCMI Usage Board is presently working on a model for accomplishing this in the context of "application profiles."

Rachel Heery and Manjula Patel, in their article "Application profiles: mixing and matching metadata schemas" define an application profile as:

" ... schemas which consist of data elements drawn from one or more namespaces, combined together by implementors, and optimised for a particular local application."

This model allows different communities to use the DC elements for core descriptive information, and allowing domain specific extensions which make sense within a more limited arena.

1.3. The Purpose and Scope of This Guide

This document is intended to be an entry point for users of Dublin Core. For non-specialists, it will assist in creating simple descriptive records for information resources (for example, electronic documents, JPEG images, video clips). Specialists may find the document a useful point of reference to the documentation of Dublin Core, as it changes and grows.

"Using Dublin Core" will show in a non-technical fashion how Dublin Core metadata may be used by anyone to make their material more accessible. It discusses the principles, structure and content of Dublin Core metadata elements, how to use them in composing a complete Dublin Core metadata record, as well as how to qualify elements to support use by a wide variety of communities.

Another important goal of this document is to promote "best practices" for describing resources using the Dublin Core element set. The Dublin Core community recognizes that consistency in creating metadata is an important key to achieving optimal retrieval and intelligible display across disparate sources of descriptive records. Inconsistent metadata effectively hides desired records, resulting in uneven, unpredictable or incomplete search results.

As a general introduction, this document is necessarily brief, and cannot address all the issues implementors may encounter while planning their use of metadata. Several avenues remain for those who have additional questions beyond those addressed in this guide.

  1. 1. Appended to this guide are references to relevant articles and other resources, including those with more technical guidance for implementors
  2. The Dublin Core Website contains references to additional documents and resources of the DCMI community and ways for implementors to become involved in the DCMI
  3. Specific questions can be addressed to AskDCMI. In addition to fielding questions, the AskDCMI service maintains a searchable archive of already answered questions and links to additional resources.

2. Syntax Issues

[/documents/abstract-model/ The Dublin Core Abstract Model] provides a reference model against which particular DC encoding guidelines can be compared, independent of any particular encoding syntax. Such a reference model allows implementors to gain a better understanding of the kinds of descriptions they are trying to encode and facilitates the development of better mappings and translations between different syntaxes. Although the document is primarily aimed at the developers of software applications that support Dublin Core metadata, anyone who is considering implementing Dublin Core -- particularly those contemplating extending DC in any way -- could usefully review the document. Those involved in developing new syntax encoding guidelines for Dublin Core metadata or developing metadata application profiles based on the Dublin Core should also become familiar with the DC Abstract Model.

In this guide, we have chosen to represent Dublin Core examples in a "generic" form (Element="value"). Examples of other syntaxes, including: HTML or XHTML (the Web's Hypertext Markup Language format), RDF/XML (the Resource Description Framework using eXtensable Markup Language) and in plain XML can be found in syntax-specific [/resources/expressions/ documents available on the DCMI Website]. Some are also referenced within this document and in the [/documents/usageguide/bibliography.shtml Bibliography Section] of this guide.

Syntax choices depend on a number of variables, and "one size fits all" prescriptions rarely apply. When considering an appropriate syntax, it is important to note that Dublin Core concepts and semantics are designed to be syntax independent, are equally applicable in a variety of contexts, as long as the metadata is in a form suitable for interpretation both by search engines and by human beings.

2.1. HTML and XHTML

HTML or XHTML can be used to express either simple or qualified Dublin Core, although there are limitations inherent in representing refinements in HTML. Specific instructions for expressing Dublin Core in HTML can be found in the following DCMI document:

  1. [/documents/dcq-html/ Expressing Qualified Dublin Core in HTML/XHTML meta and link elements]

2.2. RDF/XML

RDF (Resource Description Framework) allows multiple metadata schemes to be read by humans as well as parsed by machines. It uses XML (EXtensible Markup Language) to express structure thereby allowing metadata communities to define the actual semantics. This decentralized approach recognizes that no one scheme is appropriate for all situations, and further that schemes need a linking mechanism independent of a central authority to aid description, identification, understanding, usability, and/or exchange.

RDF allows multiple objects to be described without specifying the detail required. The underlying glue, XML, simply requires that all namespaces be defined and once defined, they can be used to the extent needed by the provider of the metadata.

For example:


   <rdf:Description rdf:about="">

      <dc:creator>Rose Bush</dc:creator>

      <dc:title>A Guide to Growing Roses</dc:title>
      <dc:description>Describes process for planting and nurturing different kinds of rose bushes.</dc:description> 



This simple example uses Dublin Core by itself to describe an audio recording of a guide to growing rose bushes. With XML or RDF/XML, Dublin Core can potentially be mixed with other metadata vocabularies. For example, the simple Dublin Core description above might be used alongside other vocabularies such as vCard that can describe the author's affiliation and contact information, or a more specialized "rose description" vocabulary that described the rose bushes in greater detail.

DCMI has made available several recommendations specifically about using these syntaxes:

  1. [/documents/dc-xml-guidelines/ Guidelines for Implementing Dublin Core in XML]
  2. [/documents/dcmes-xml/ Expressing Simple Dublin Core in RDF/XML]
  3. [/documents/dcq-rdf-xml/ Expressing Qualified Dublin Core in RDF/XML] (Proposed Recommendation)

2.3. Metadata Storage and Maintenance Issues

Some implementations using Dublin Core have chosen to embed their metadata within the resource itself. This approach is taken most often with documents encoded using HTML, but is also sometimes possible with other kinds of documents. Simple tools have been developed to make provision of Dublin Core metadata within HTML encoded pages fairly easy. One such tool,, extracts metadata information from an HTML document, and formats it so that it can be edited, then cut and pasted back into the HTML header of the original document.

On the other hand, metadata can be stored in any kind of database, and provide a link to the described resource rather than be embedded within it. This approach is likely to be most practical for many non-textual resources, and is increasingly used for text as well, primarily to support easier maintenance and sharing of metadata.

Each of these approaches have their advantages and disadvantages, and the balance point changes as implementations become larger and more diverse, and also as the metadata ages over time.

3. Element Content and Controlled Vocabularies

Each Dublin Core element is optional and repeatable, and there is no defined order of elements. 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 user environment. Ordering or sequencing may be syntax dependent; for instance, RDF/XML supports ordering, but HTML does not.

Content data for some elements may be selected from a "controlled vocabulary," which is a limited set of consistently used and carefully defined terms. This can dramatically improve search results because computers are good at matching words character by character but weak at understanding the way people refer to one concept using different words, i.e. synonyms. Without basic terminology control, inconsistent or incorrect metadata can profoundly degrade the quality of search results. For example, without a controlled vocabulary, "candy" and "sweet" might be used to refer to the same concept. Controlled vocabularies may also reduce the likelihood of spelling errors when recording metadata.

One cost of a controlled vocabulary is the necessity for an administrative body to review, update and disseminate the vocabulary. For example, the US Library of Congress Subject Headings (LCSH) and the US National Library of Medicine Medical Subject Headings (MeSH) are formal vocabularies, indispensable for searching rigorously cataloged collections. However, both require significant support organizations. Another cost is having to train searchers and creators of metadata so that they know when using MeSH, for example, to enter "myocardial infarction" instead of the more colloquial "heart attack." More sophisticated implementations can make such tasks much easier, but the controlled vocabulary terms must be available for them to apply.

Using controlled vocabularies can be done most effectively using [/documents/dcmi-terms/#H4 encoding schemes]. Without an encoding scheme specifically designated, a subject which might very well be carefully selected from a particular controlled vocabulary cannot be distinguished from a simple keyword.

4. [/documents/usageguide/elements.shtml The Elements]

Using Dublin Core - The Elements

4. The Elements

This section lists each element by its full name and label. For each element there are guidelines to assist in creating metadata content, whether it is done "from scratch" or by converting an existing record in another format.

In the element descriptions below, a formal single-word label is specified 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 converted to a case-sensitive environment, such as XML.

Some information may appear to belong in more than one metadata element. While there will normally be a clear preferred choice, there is potential semantic overlap between some elements. Consequently, there will occasionally be some judgment required from the person assigning the metadata.

4.1. Title

Label: Title

Element Description: The name given to the resource. Typically, a Title will be a name by which the resource is formally known.

Guidelines for creation of content:

If in doubt about what constitutes the title, repeat the Title element and include the variants in second and subsequent Title iterations. If the item is in HTML, view the source document and make sure that the title identified in the title header (if any) is also included as a Title.


Title="A Pilot's Guide to Aircraft Insurance"
Title="The Sound of Music"
Title="Green on Greens"
Title="AOPA's Tips on Buying Used Aircraft"

4.2. Subject

Label: Subject and Keywords

Element Description: The topic of the content of the resource. Typically, a Subject will be expressed as keywords or key phrases or classification codes that describe the topic of the resource. Recommended best practice is to select a value from a controlled vocabulary or formal classification scheme.

Guidelines for creation of content:

Select subject keywords from the Title or Description information, or from within a text resource. If the subject of the item is a person or an organization, use the same form of the name as you would if the person or organization were a Creator or Contributor.

In general, choose the most significant and unique words for keywords, avoiding those too general to describe a particular item. Subject might include classification data if it is available (for example, Library of Congress Classification Numbers or Dewey Decimal numbers) or controlled vocabularies (such as Medical Subject Headings or Art and Architecture Thesaurus descriptors) as well as keywords.

When including terms from multiple vocabularies, use separate element iterations. If multiple vocabulary terms or keywords are used, either separate terms with semi-colons or use separate iterations of the Subject element.


Subject="Aircraft leasing and renting"
Subject="Olympic skiing"
Subject="Street, Picabo"

4.3. Description

Label: Description

Element Description: An account of the content of the resource. Description may include but is not limited to: an abstract, table of contents, reference to a graphical representation of content or a free-text account of the content.

Guidelines for creation of content:

Since the Description field is a potentially rich source of indexable terms, care should be taken to provide this element when possible. Best practice recommendation for this element is to use full sentences, as description is often used to present information to users to assist in their selection of appropriate resources from a set of search results.

Descriptive information can be copied or automatically extracted from the item if there is no abstract or other structured description available. Although the source of the description may be a web page or other structured text with presentation tags, it is generally not good practice to include HTML or other structural tags within the Description element. Applications vary considerably in their ability to interpret such tags, and their inclusion may negatively affect the interoperability of the metadata.


Description="Illustrated guide to airport markings and lighting signals, with particular reference to SMGCS (Surface Movement Guidance and Control System) for airports with low visibility conditions."

Description="Teachers Domain is a multimedia library for K-12 science educators, developed by WGBH through funding from the National Science Foundation as part of its National Science Digital Library initiative. The site offers a wealth of classroom-ready instructional resources, as well as online professional development materials and a set of tools which allows teachers to manage, annotate, and share the materials they use in classroom teaching."

4.4. Type

Label: Resource Type

Element Description: The nature or genre of the content of the resource. 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 DCMIType vocabulary ). To describe the physical or digital manifestation of the resource, use the FORMAT element.

Guidelines for content creation:

If the resource is composed of multiple mixed types then multiple or repeated Type elements should be used to describe the main components.

Because different communities or domains are expected to use a variety of type vocabularies, best practice to ensure interoperability is to include at least one general type term from the DCMIType vocabulary in addition to the domain specific type term(s), in separate Type element iterations.



Note: The first three values are taken from the DCMI Type Vocabulary, and follow the capitalization conventions for that vocabulary. The last value is a term from an unspecified source.

The item described is an Electronic art exhibition catalog:

Type="Exhibition catalog"

Note: The first two values are taken from the DCMI Type Vocabulary, and follow the capitalization conventions for that vocabulary. The last value is a term from an unspecified source.

The item described is a Multimedia educational program with interactive assignments:


Note: All values in this example are taken from the DCMI Type Vocabulary, and follow the capitalization conventions for that vocabulary.

4.5. Source

Label: Source

Element Description: A Reference to a resource from which the present resource is derived. The present resource may be derived from the Source resource in whole or part. Recommended best practice is to reference the resource by means of a string or number conforming to a formal identification system.

Guidelines for content creation:

In general, include in this area information about a resource that is related intellectually to the described resource but does not fit easily into a Relation element.


Source="RC607.A26W574 1996" [where "RC607.A26W574 1996" is the call number of the print version of the resource, from which the present version was scanned]

Source="Image from page 54 of the 1922 edition of Romeo and Juliet"

4.6. Relation

Label: Relation

Element Description: A reference to a related resource. Recommended best practice is to reference the resource by means of a string or number conforming to a formal identification system.

Guidelines for content creation:

Relationships may be expressed reciprocally (if the resources on both ends of the relationship are being described) or in one direction only, even when there is a refinement available to allow reciprocity. If text strings are used instead of identifying numbers, the reference should be appropriately specific. For instance, a formal bibliographic citation might be used to point users to a particular resource.

Because the refined terms used with Relation provide significantly more information to a user than the unqualified use of Relation, implementers who are describing heavily interrelated resources might choose to use qualified Dublin Core.


Title="Reading Turgenev"
Relation="Two Lives" [Resource is a collection of two novellas, one of which is "Reading Turgenev"]
[Relationship described is IsPartOf.

[Part/Whole relations are those in which one resource is a physical or logical part of another]

Title="Candle in the Wind"
Subject="Diana, Princess of Wales"
Creator="John, Elton"
Description="Tribute to a dead princess."
Relation="Elton John's 1976 song Candle in the Wind"
[Relationship described is IsVersionOf.

[Version relations are those in which one resource is an historical state or edition, of another resource by the same creator]

Title="Electronic AACR2"
Relation="Anglo-American Cataloging Rules, 2nd edition"
[Relationship described is IsFormatOf]
Title="Landsat TM dataset of Arnhemland, NT, Australia"
[Relationship described is HasFormat]

[Format transformation relations are those in which one resource has been derived from another by a reproduction or reformatting technology which is not fundamentally an interpretation but intended to be a representation.]

Title="Morgan's Ancient Society"
Relation="Engels' Origin of the Family, Private Property and the State"
[Relationship described is IsReferencedBy]
Title="Nymphet Mania"
Relation="References Adrian Lyne's 'Lolita'"
[Relationship described is References]

[Reference relations are those in which the author of one resource cites, acknowledges, disputes or otherwise make claims about another resource.]

Title="Peter Carey's novel Oscar and Lucinda"
Relation="1998 movie Oscar and Lucinda"
[Relationship described is IsBasisFor]
Title="The movie My Fair Lady"
Relation="Shaw's play Pygmalion"
[Relationship described is IsBasedOn]

[Creative relations are those in which one resource is a performance, production, derivation, adaptation or interpretation of another resource.]

Title="Dead Ringer"
Relation="Gemstar e-book"
[Relationship described is Requires]

[Dependency relations are those in which one resource requires another resource for its functioning, delivery, or content and cannot be used without the related resource being present.]

4.7. Coverage

Label: Coverage

Element Description: The extent or scope of the content of the resource. Coverage will typically include spatial location (a place name or geographic co-ordinates), 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 [Getty Thesaurus of Geographic Names, http://www.]). Where appropriate, named places or time periods should be used in preference to numeric identifiers such as sets of co-ordinates or date ranges.

Guidelines for content creation:

Whether this element is used for spatial or temporal information, care should be taken to provide consistent information that can be interpreted by human users, particularly in order to provide interoperability in situations where sophisticated geographic or time-specific searching is not supported. For most simple applications, place names or coverage dates might be most useful. For more complex applications, consideration should be given to using an encoding scheme that supports appropriate specification of information, such as DCMI Period, DCMI Box or DCMI Point.


Coverage="Boston, MA"
Coverage="17th century"
Coverage="Upstate New York"

4.8. Creator

Label: Creator

Element Description: An entity primarily responsible for making the content of the resource. Examples of a Creator include a person, an organization, or a service. Typically the name of the Creator should be used to indicate the entity.

Guidelines for creation of content:

Creators should be listed separately, preferably in the same order that they appear in the publication. Personal names should be listed surname or family name first, followed by forename or given name. When in doubt, give the name as it appears, and do not invert.

In the case of organizations where there is clearly a hierarchy present, list the parts of the hierarchy from largest to smallest, separated by full stops and a space. If it is not clear whether there is a hierarchy present, or unclear which is the larger or smaller portion of the body, give the name as it appears in the item.

If the Creator and Publisher are the same, do not repeat the name in the Publisher area. If the nature of the responsibility is ambiguous, the recommended practice is to use Publisher for organizations, and Creator for individuals. In cases of lesser or ambiguous responsibility, other than creation, use Contributor.


Creator="Shakespeare, William"
Creator="Wen Lee"
Creator="Hubble Telescope"
Creator="Internal Revenue Service. Customer Complaints Unit"

4.9. Publisher

Label: Publisher

Element Description: The entity responsible for making the resource available. Examples of a Publisher include a person, an organization, or a service. Typically, the name of a Publisher should be used to indicate the entity.

Guidelines for content creation:

The intent of specifying this field is to identify the entity that provides access to the resource. If the Creator and Publisher are the same, do not repeat the name in the Publisher area. If the nature of the responsibility is ambiguous, the recommended practice is to use Publisher for organizations, and Creator for individuals. In cases of ambiguous responsibility, use Contributor.


Publisher="University of South Where"
Publisher="Funky Websites, Inc."
Publisher="Carmen Miranda"

4.10. Contributor

Label: Contributor

Element Description: An entity responsible for making contributions to the content of the resource. Examples of a Contributor include a person, an organization or a service. Typically, the name of a Contributor should be used to indicate the entity.

Guideline for content creation:

The same general guidelines for using names of persons or organizations as Creators apply here. Contributor is the most general of the elements used for "agents" responsible for the resource, so should be used when primary responsibility is unknown or irrelevant.

4.11. Rights

Label: Rights Management

Element Description: Information about rights held in and over the resource. Typically a Rights element 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 can be made about the status of these and other rights with respect to the resource.

Guidelines for content creation:

The Rights element may be used for either a textual statement or a URL pointing to a rights statement, or a combination, when a brief statement and a more lengthy one are available.


Rights="Access limited to members"
Rights=" quot;

4.12. Date

Label: Date

Element Description: A date associated with an event in the life cycle of the resource. 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 [Date and Time Formats, W3C Note, datetime] and follows the YYYY-MM-DD format.

Guidelines for content creation:

If the full date is unknown, month and year (YYYY-MM) or just year (YYYY) may be used. Many other schemes are possible, but if used, they may not be easily interpreted by users or software.



4.13. Format

Label: Format

Element Description: The physical or digital manifestation of the resource. Typically, Format may include the media-type or dimensions of the resource. Examples of dimensions include size and duration. Format may be used to determine the software, hardware or other equipment needed to display or operate the resource.

Recommended best practice is to select a value from a controlled vocabulary (for example, the list of Internet Media Types [ assignments/media-types/] defining computer media formats).

Guidelines for content creation:

In addition to the specific physical or electronic media format, information concerning the size of a resource may be included in the content of the Format element if available. In resource discovery size, extent or medium of the resource might be used as a criterion to select resources of interest, since a user may need to evaluate whether they can make use of the resource within the infrastructure available to them.

When more than one category of format information is included in a single record, they should go in separate iterations of the element.


Title="Dublin Core icon"
Identifier=" quot;
Format="4 kB"
Format="image/gif 6"
Format="40 x 512 pixels"
Identifier=" "
Title="The Bronco Buster"
Creator="Frederic Remington"
Type="Physical object"
Format="22 in."

4.14. Identifier

Label: Resource Identifier

Element Description: An unambiguous reference to the resource within a given context. Recommended best practice is to identify the resource by means of a string or number conforming to a formal identification system. Examples of formal identification systems include the Uniform Resource Identifier (URI) (including the Uniform Resource Locator (URL), the Digital Object Identifier (DOI) and the International Standard Book Number (ISBN).

Guidelines for content creation:

This element can also be used for local identifiers (e.g. ID numbers or call numbers) assigned by the Creator of the resource to apply to a particular item. It should not be used for identification of the metadata record itself.


Identifier=" quot;
Identifier="H-A-X 5690B" [publisher number]

4.15. Language

Label: Language

Element Description: A language of the intellectual content of the resource. Recommended best practice for the values of the Language element is defined by RFC 3066 [RFC 3066, rfc3066.txt] which, in conjunction with ISO 639 [ISO 639, http://www.oasis-]), 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.

Guidelines for content creation:

Either a coded value or text string can be represented here. If the content is in more than one language, the element may be repeated.


Language="Primarily English, with some abstracts also in French."

NOTE: Audience, Provenance and RightsHolder are elements, but not part of the Simple Dublin Core fifteen elements. Use Audience, Provenance and RightsHolder only when using Qualified Dublin Core.

4.16. Audience

Label: Audience

Element Description: A class of entity for whom the resource is intended or useful. A class of entity may be determined by the creator or the publisher or by a third party.

Guidelines for content creation:

Audience terms are best utilized in the context of formal or informal controlled vocabularies. None are presently recommended or registered by DCMI, but several communities of interest are engaged in setting up audience vocabularies. In the absence of recommended controlled vocabularies, implementors are encouraged to develop local lists of values, and to use them consistently.


Audience="elementary school students"
Audience="ESL teachers"
Audience="deaf adults"

4.17. Provenance

Label: Provenance

Element Description: A statement of any changes in ownership and custody of the resource since its creation that are significant for its authenticity, integrity and interpretation. The statement may include a description of any changes successive custodians made to the resource.

Guidelines for content creation:


Provenance="This copy once owned by Benjamin Spock."
Provenance="Estate of Hunter Thompson."
Provenance="Stolen in 1999; recovered by the Museum in 2003."

4.18. RightsHolder

Label: Rights Holder

Element Description: A person or organization owning or managing rights over the resource. Recommended best practice is to use the URI or name of the Rights Holder to indicate the entity.

Guidelines for content creation:

Since, for the most part, people and organizations are not typically assigned URIs, a person or organization holding rights over a resource would be named using a text string. People and organizations sometimes have websites, but URLs for these are not generally appropriate for use in this context, since they are not clearly identifying the person or organization, but rather the location of a website about them.


RightsHolder="Stuart Weibel"
RightsHolder="University of Bath"

4.19. InstructionalMethod

Label: Instructional Method

Element Description: A process, used to engender knowledge, attitudes and skills, that the resource is designed to support. Instructional Method will typically include ways of presenting instructional materials or conducting instructional activities, patterns of learner-to-learner and learner-to-instructor interactions, and mechanisms by which group and individual levels of learning are measured. Instructional methods include all aspects of the instruction and learning processes from planning and implementation through evaluation and feedback.

Guidelines for content creation:

Best practice is to use terms from controlled vocabularies, whether developed for the use of a particular project or in general use in an educational context.


InstructionalMethod="Experiential learning"
InstructionalMethod="Large Group instruction"

4.20. AccrualMethod

Label: Accrual Method

Element Description: The method by which items are added to a collection. Recommended best practice is to use a value from a controlled vocabulary.

Guidelines for content creation:

Terms from controlled vocabularies may be developed for the use of a particular project or in general use in a cultural materials context.



4.21. AccrualPeriodicity

Label: Accrual Periodicity

Element Description: The frequency with which items are added to a collection. Recommended best practice is to use a value from a controlled vocabulary.

Guidelines for content creation:

Terms from controlled vocabularies may be developed for the use of a particular project or in general use in a cultural materials context.



4.22. AccrualPolicy

Label: Accrual Policy

Element Description: The policy governing the addition of items to a collection. Recommended best practice is to use a value from a controlled vocabulary.

Guidelines for content creation:

Terms from controlled vocabularies may be developed for the use of a particular project or in general use in a cultural materials context.




2006-02-07: Corrected spelling (s/Languge/Language/)
2006-08-28, Errata: 'Type="Interactive Resource"' changed to 'Type="InteractiveResource"' in Section 4.4.

Using Dublin Core - Dublin Core Qualifiers

5. Dublin Core Qualifiers

This document presents in part the results of an ongoing process to develop exemplary terms extending or refining the original 15 elements of the Dublin Core Metadata Element Set (DCMES). The terms or "qualifiers" listed here were identified, generally in working groups of the Dublin Core Metadata Initiative, (DCMI) and judged by the DCMI Usage Board to be in conformance with principles of good practice for the qualification of Dublin Core metadata elements.

In determining the makeup of these qualifiers, preference was given to vocabularies, notations, and terms already maintained by established agencies. It should be emphasized that the list of externally-maintained vocabularies identified here is a preliminary list. There are many more controlled vocabularies or classification systems that are not on this list. Detail on currently recommended schemes are listed at: DCMI Encoding Schemes - a current list

Inevitably, there will be situations where an agent or client will encounter DCMES descriptions that use unfamiliar qualifiers developed by implementors for specialized local or domain-specific needs. The useful interpretation of such a DCMES description will depend on the ability of an application to ignore the unknown qualifiers and fall back on the broader meaning of the element in its unqualified form. The guiding principle for the qualification of Dublin Core elements, colloquially known as the "Dumb-Down Principle," is that a client should be able to ignore any qualifier and use the information as if it were unqualified. 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.

It is expected that implementors will develop additional qualifiers for use within local applications or specific domains. Such qualifiers may not be understood by other applications. However, qualifiers that conform to the principles of qualification defined here are more likely to be reusable by other communities within the broader context of cross-domain discovery.

At the time of the ratification of this document, the DCMI recognizes two broad classes of qualifiers:

  • Element Refinement. These qualifiers make the meaning of an element narrower or more specific. A refined element shares the meaning of the unqualified element, but with a more restricted scope. A client 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. The definitions of element refinement terms for qualifiers must be publicly available.
  • Encoding Scheme. These qualifiers identify schemes that aid in the interpretation of an element value. These schemes include controlled vocabularies and formal notations or parsing rules. A value expressed using an encoding scheme will thus be a token selected from a controlled vocabulary (e.g., a term from a classification system or set of subject headings) or a string formatted in accordance with a formal notation (e.g., "2000-01-01" as the standard expression of a date). If an encoding scheme is not understood by a client or agent, the value may still be useful to a human reader. The definitive description of an encoding scheme for qualifiers must be clearly identified and available for public use.

All of the qualifiers listed in this document fall into one of these two categories. Specific guidance is given below for element refinements. If a particular encoding scheme is available for the element and or/element refinement, its application is generally described either in this document or in documentation available with the encoding scheme itself. Audience, Provenance and RightsHolder, which are at the element level but not one of the original 15 elements, are described along with the other elements.

Additional qualifier categories may evolve over time and with implementation experience. The qualifiers listed here do not constitute a closed set, designed to meet all of the descriptive needs of implementors. Rather, they form the foundation for a larger body of qualifiers that will evolve as additional qualifiers are developed by various communities, some of which may eventually be submitted to the DCMI Usage Board for review and approval. Implementors may deploy the qualifiers on these lists with confidence that they conform to the Dumb-Down Principle, and are encouraged to use these qualifiers as examples to guide development of local qualifiers for Dublin Core metadata elements.

Summary Refinement and Scheme Table

This summary of the element refinements and schemes is provided for the convenience of users. Terms in this summary may have the status of "recommended" or "conforming." The reference definitions and status indications may be found in DCMI Terms. Click on the term to go directly to the reference definition for that term.

DCMES Element Element Refinement(s) Element Encoding Scheme(s)





- -





Table Of Contents



- -


- -


Date Accepted Date Copyrighted
Date Submitted

DCMI Period



DCMI Type Vocabulary











Bibliographic Citation







ISO 639-2RFC 3066


Is Version Of
Has Version
Is Replaced By
Is Required By
Is Part Of
Has Part
Is Referenced By
Is Format Of
Has Format
Conforms To




DCMI Point
ISO 3166


DCMI Period


Access Rights





Education Level



- -

Rights Holder

- -

Instructional Method

- -

Accrual Method

- -

Accrual Periodicity

- -

Accrual Policy

- -

Properties of Dublin Core Qualifiers

Dublin Core qualifiers have the following properties:

  • Name: The unique token assigned to the qualifier.
  • Label: The human-readable label assigned to the qualifier.
  • Definition: A statement that represents the concept and essential nature of the qualifier.
  • Comment: Additional information associated with the qualifier (if available).
  • See Also: A link to more information about the qualifier (if available).

For the up-to-date specification of all metadata terms maintained by the Dublin Core Metadata Initiative, including elements, element refinements, encoding schemes, and vocabulary terms (the DCMI Type Vocabulary), see In the listing below, the Name and Label attributes are the same as in the specification, but the Definition and Comment appear together as "Term Description", and guidance and examples are added.

Multiple Language Encodings of Dublin Core Entities

Dublin Core qualifiers will be expressed in languages other than English. A single invariant token assigned to each qualifier -- the Name property -- stands for a given qualifier concept irrespective of the language in which it is defined. This token can be incorporated into a URI to form a unique identifier for the qualifier. All other properties of a qualifier (Label, Definition, Comment, and aspects of See Also as appropriate) can be translated from English into any other language.

All other properties of Dublin Core entities (Label, Definition, Comment, and aspects of See Also as appropriate) will be expressed in the language and character set of the translation.

Element Refinements

These element refinement terms are extensions to the "Simple Dublin Core" 15 elements or to the additional element terms Audience, Provenance and RightsHolder.

Refinement(s) for element: Title


Label: Alternative

Term description: Any form of the title used as a substitute or alternative to the formal title of the resource. This qualifier can include Title abbreviations as well as translations.

Guidelines for creation of content:

An alternative title can be used to provide access to secondary titles, but should only be used when a value is present in the Title element.


Alternative="AMA newsletter" (Title="American Meteorological Association newsletter")
Alternative="Ocho semanas" (Title="Eight weeks")

Refinement(s) for element: Description


Label: Table of Contents

Term description: A list of subunits of the content of the resource.

Guidelines for creation of content:

When a description of a resource consists of a list of the contents, whether from a menu or other mechanism, tableOfContents can be used to differentiate this list from descriptive text that is written in sentence form. This allows more options for display and indexing.


tableOfContents="Introduction; Vertebrates; Invertebrates; Molluscs"


Label: Abstract

Term description: A summary of the content of the resource.

Guidelines for creation of content:

Used when a description of a resource consists of a formal abstract. For implementations where formal abstracts are preferred, using the specific term allows the label to better reflect the level of the description.


Abstract="This article describes the work of the IFB Chaos Committee, including a summary of its major findings."

Refinement(s) for element: Date

Date refinements are generally useful in situations where more than one date is needed, and the difference between the dates may be important to users. Note that the first five Date refinement terms were among the earlier ones approved by DCMI, and the naming convention of the time was not to include "date" as part of the refined term. The most recent ones reflect changes in the naming convention used, in which the name of the refined term expresses more clearly the relationship to the parent element. When using date refinements it can be unwise to insert a text string that repeats the distinction created by the refinement itself. For instance, the string "Valid 20010211" in a statement where the refinement "valid" is used might show up in a labelled display as: VALID: Valid 20010211.


Label: Created

Term description: Date of creation of the resource.

Guidelines for creation of content:

If the date of creation of the resource is known, and that date is important to note specifically (e.g., there are other relevant dates to record), use the term Created for the creation date of the resource. Note that the "one-to-one" rule requires that the creation date be that of the resource being described, not any early version from which the current resource is derived.


Label: Valid

Term description: Date (often a range) of validity of a resource.

Guidelines for creation of content:

If the resource is only valid or relevant for a particular date or range of dates, the term Valid may be used to express those dates. This may be particularly important if the resource will be retained over time but its use is valid only during a particular period or until a particular date.


Label: Available

Term description: Date (often a range) that the resource will become or did become available.

Guidelines for creation of content:

In general, the term Available should be used in the case of a resource for which the date of availability may be distinct from the date of creation, and the date of availability is relevant to the use of the resource.


Label: Issued

Term description: Date of formal issuance (e.g., publication) of the resource.

Guidelines for creation of content:

The term Issued should be applied when a formal date of issuance or publication is relevant to the resource, and is distinct from other dates that may be used with the resource.


Label: Modified

Term description: Date on which the resource was changed.

Guidelines for creation of content:

Modified dates may be used to record either all instances of modification or only the latest. When only one modified date is recorded, it is assumed to be the latest.


Label: Date Accepted

Term description: Date of acceptance of the resource (e.g. of thesis by university department, of article by journal, etc.).

Guidelines for creation of content:

If, in the lifecycle of a resource, the date of acceptance by a formal body or entity is relevant to the use of the resource, dateAccepted may be used.


Label: Date Copyrighted

Term description: Date of a statement of copyright.

Guidelines for creation of content:

If, in the lifecycle of a resource, the date of copyright is relevant to the use of the resource, dateCopyrighted may be used.


Label: Date Submitted

Term description: Date of submission of the resource (e.g. thesis, articles, etc.).

Guidelines for creation of content:

If, in the lifecycle of a resource, the date of submission to a body or entity is relevant to the use of the resource, dateSubmitted may be used.

Refinement(s) for element: Format


Label: Extent

Term description: The size or duration of the resource.

Guidelines for creation of content:

Because the refinement Extent is used in a variety of situations, it generally consists of both a numeric value and a caption that is needed to interpret the numeric value. Best practice is to separate the numeric value and the caption with a space, whether the caption appears before or after the value.


Extent="899 Kb"
Extent="21 minutes"


Label: Medium

Term description: The material or physical carrier of the resource.

Guidelines for creation of content:

Medium is generally used when the resource is of a physical nature, for instance a painting or model, where the physical carrier or material used is relevant to the user. For instance, if the resource is a movie on DVD, and is only available as a physical object, it should be described as such. If it is available digitally, for download or presentation on a website, its format would be reflected in the Format element. Note that, because of the physical nature of materials described with this refinement, the encoding scheme "IMT" is not valid for use with Medium.


Medium="cotton fabric with sequins"
Medium="bronze on wooden pedestal"
Medium="oil on wood"

Refinement(s) for element: Relation

Most of the refinements of Relation are expressed as "reciprocals" and may be used to link resources in two directions, though this is not required. Implementors need not describe both or all resources involved in a reciprocal relationship to express the relationship--in other words, they may describe a later version and relate it to the earlier without having the need or opportunity to describe the earlier, and vice versa. In some of the relationships below, maintaining reciprocality is more important. In others, one direction of the relationship is more relevant that the other. These differences will be mentioned in the guidelines for specific terms.

In All cases, either a string or a URI may be used as a value. If a URI is used, the scheme should be designated.

Examples for Relation refinements can be found with the Relation element. When using Relation refinements, do not use embedded text labels, as the examples illustrate.


Label: Is Version Of

Term description: The described resource is a version, edition, or adaptation of the referenced resource. Changes in version imply substantive changes in content rather than differences in format.

Guidelines for creation of content:

Use only in cases where the relationship expressed is at the content level. Relationships need not be close for the relationship to be relevant. "West Side Story" is a version of "Romeo and Juliet" and that may be important enough in the context of the resource description to be expressed using isVersionOf. The Broadway Show and the movie of "West Side Story" also relate at a similar level, but the video and DVD of the movie are more usefully expressed at the level of format, the content being essentially the same.

See also isFormatOf.


Label: Has Version

Term description: The described resource is a version, edition, or adaptation of the referenced resource. Changes in version imply substantive changes in content rather than differences in format.

Guidelines for creation of content:

See isVersionOf for basic guidelines.


Label: Is Replaced By

Term description: The described resource is supplanted, displaced, or superseded by the referenced resource.

Guidelines for creation of content:

When establishing a chain of versions, where only one version is valid, the use of isReplacedBy and Replaces allows the relationship to be expressed and the user directed to the appropriate version. In this case, the reciprocal relationships are quite important.


Label: Replaces

Term description: The described resource supplants, displaces, or supersedes the referenced resource.

Guidelines for creation of content:

See isReplacedBy for basic guidelines.


Label: Is Required By

Term description: The described resource is required by the referenced resource, either physically or logically.

Guidelines for creation of content:

In the case of IsRequiredBy and Requires, there is a clearer need to express the Requires relationship than the IsRequiredBy, though both can be useful. This relationship is most often seen in relationships between software and documents or applications and hardware and/or software requirements.


Label: Requires

Term description: The described resource requires the referenced resource to support its function, delivery, or coherence of content.

Guidelines for creation of content:

See isRequiredBy for basic guidelines.


Label: Is Part Of

Term description: The described resource is a physical or logical part of the referenced resource.

Guidelines for creation of content:

The isPartOf and hasPart relationships are essentially "parent/child" relationships--hierarchical in nature. With them can be expressed both one-to-one and one-to-many types of relationships.


Label: Has Part

Term description: The described resource includes the referenced resource either physically or logically.

Guidelines for creation of content:

See isPartOf for basic guidelines.


Label: Is Referenced By

Term description: The described resource is referenced, cited, or otherwise pointed to by the referenced resource.

Guidelines for creation of content:

The isReferencedBy and References refinements enable the expression of relationships that aid the user but are not necessary tied to the lifecycle or necessary for the intended use of the resource. This relationship might be used to link an article critical of a resource to that resource, a satire of a speech to the original speech, etc.


Label: References

Term description: The described resource references, cites, or otherwise points to the referenced resource.

Guidelines for creation of content:

See isReferencedBy for basic guidelines.


Label: Is Format Of

Term description: The described resource is the same intellectual content of the referenced resource, but presented in another format.

Guidelines for creation of content:

This relationship is explicitly for the expression of relationships between resources for which format is the primary variable. Because Dublin Core maintains the principle of "one-to-one," each resource is expected to have its own description.

See also isVersionOf.


Label: Has Format

Term description: The described resource pre-existed the referenced resource, which is essentially the same intellectual content presented in another format.

Guidelines for creation of content:

See isFormatOf for basic guidelines.


Label: Conforms To

Term description: A reference to an established standard to which the resource conforms.

Guidelines for creation of content:

The standards referenced might be educational standards, accessibility standards, or any other established standard that is relevant to the use of the resource.

Refinement(s) for element: Coverage


Label: Spatial

Term description: Spatial characteristics of the intellectual content of the resource.

Guidelines for creation of content:

Spatial characteristics may include geographic names, latitude/longitude, or other established georeferenced values. Clearly, this refinement does not allow complex or sophisticated georeferencing, but attention to standard schemes and controlled vocabularies should provide useful results. Controlled vocabulary terms can be drawn from recommended vocabularies, or standard labelling within the value can provide useful assistance to users and applications. For additional information on encoding spatial information see the DCMI Box Encoding Scheme and the DCMI Point Encoding Scheme.


Spatial="Chicago, Ill."
Spatial="Lat: 44 00 00 S Long: 068 00 00 W Name: Patagonia"
Spatial="Upstate New York"


Label: Temporal

Term description: Temporal characteristics of the intellectual content of the resource.

Guidelines for creation of content:

Temporal characteristics include those aspects of time that relate to the intellectual content of a resource and not its lifecycle. Examples might include a resource describing some aspect of the 19th century but itself created this year. In that case, the Temporal Coverage would be the 19th century, and the Date (or Date Created) would be 2003. Values can be text strings or encoded values. Specific suggestions for encoding Temporal characteristics may be found in the DCMI Period Encoding Scheme.


Temporal="Jurassic Period"
Temporal="Twentieth Century"

Refinement(s) for element: Audience


Label: Mediator

Term description: A class of entity that mediates access to the resource and for whom the resource is intended or useful. The audiences for a resource are of two basic classes: (1) an ultimate beneficiary of the resource, and (2) frequently, an entity that mediates access to the resource. The mediator element refinement represents the second of these two classes.

Guidelines for creation of content:

In an educational setting, a teacher might be designated the Mediator for a resource intended for use by a teacher in a classroom of students of a particular level or sharing other similar characteristics. Resources intended to be used directly by those same students would not include a Mediator. Mediators may be expressed in more or less specific terms, depending on the needs of the implementation. Controlled vocabularies can be useful in distinguishing Mediators.


Mediator="Reading specialist"
Mediator="ESL teachers"


Label: Education Level

Term description: A general statement describing the education or training context. Alternatively, a more specific statement of the location of the audience in terms of its progression through an education or training context.

Guidelines for creation of content:

Commonly, this term would be used for a grade level for materials intended for an educational setting. Although no specific controlled vocabulary has been recommended for use with educationLevel, consistent use of terminology or reliance on an available controlled vocabulary enables more consistent results.


educationLevel="elementary school students"
educationLevel="4th-5th grade"
educationLevel="secondary science"

Refinement(s) for element: Rights


Label: Access Rights

Term description: Information about who can access the resource or an indication of its security status. Access Rights may include information regarding access or restrictions based on privacy, security or other regulations.

Guidelines for creation of content:

Access rights is intended to allow the characterization of restrictions to view, search or use resources, based on attributes of the resource itself or the class or category of user. An example would be a resource that was restricted to users holding a particular security clearance, or one that required login or authentication at a particular website.


accessRights="Available to subscribers only."
accessRights="Viewable by Medium security cleared staff only."


Label: License

Term description: A legal document giving official permission to do something with the resource. Recommended best practice is to identify the license using a URI. Examples of such licenses can be found at

Guidelines for creation of content:

License is designed to allow the inclusion of specific licensed uses to be specified. An example would be a resource that was available to be used freely but not for reproduction within commercial applications.


license=" legalcode"
license="Licensed for use under Creative Commons Attribution 2.0."

Refinement(s) for element: Identifier


Label: Bibliographic Citation

Term description: A bibliographic reference for the resource. Recommended practice is to include sufficient bibliographic detail to identify the resource as unambiguously as possible, whether or not the citation is in a standard form.

Guidelines for creation of content:

Because this term is not describing a relationship to another resource, it should be limited to citations to the resource described in the remainder of the record. For instance, if the resource is an article for a journal, it is appropriate to include very specific information about the article, even page references, if such information is used to cite the article in a standard format for reference by other resources, even if the article being described is in a digital format.


bibliographicCitation="ESOP, v.2, no. 1, Apr. 2003, p. 5-8"
bibliographicCitation="Nature, v.87, p. 200"

For additional guidance on using this refinement, see: Guidelines for Encoding Bibliographic Citation Information in Dublin Core.

Using Dublin Core - Appendix, Roles

6. Using Agent Roles in Dublin Core


MARC Relator terms are properties used to describe the relationship of an agent to a resource by specifying the particular nature of the relationship. They can be used to describe the various roles people and organizations play in the development and use of a resource. The property "Illustrator", for example, can be used for an agent which provided illustrations for the resource.

In Dublin Core, agent roles are expressed as properties (i.e., elements or element refinements). As explained below, most are refinements of the element dc:contributor. In order to identify a subset of MARC Relator Terms as refinements of dc:contributor, DCMI and the Library of Congress cooperated on the evaluation of all (circa) 150 MARC Relator Terms with regard to whether they represented "an entity responsible for making contributions to the content of the resource."

The MARC Relator List: What It Is and How It's Structured

The MARC Code List for Relators was developed for use in MARC 21 bibliographic records to express the relationship between a name and a work. The list includes both role terms and three-character codes representing those terms. The terms were only included on the list when the name and its associated role were considered important enough to include on a bibliographic record as an access point. The Library of Congress is the maintenance agency for this list and regularly adds new terms when a need is expressed and documented. The agreement between DCMI and the Library of Congress specifies that new terms submitted to LC will be referred to the DCMI Usage Board for endorsement of sub-property relationships asserted with regard to Dublin Core elements. This agreement is described in the Web document "MARC Relator Terms and Dublin Core".

The MARC Relator list includes three-character alphabetic codes to be used to identify roles. In addition the list provides definitions for the terms (and associated codes). In MARC records, the codes are synonyms for the term they represent. In DC metadata descriptions, properties are referred to using unique identifiers (URIs), and the codes were used to form unique identifiers for these properties. The list of MARC Relator Terms is maintained by the Library of Congress, so the terms have been assigned URIs on the basis of a namespace established by LC. Schemas or instance metadata will need to cite these URIs (or the MARC relator namespace) in order to use any of the MARC Relator properties, be they sub-properties of Dublin Core elements or not. See the document "Guidelines for Implementing Dublin Core in XML" for specific information on using non-DCMI namespaces.

In addition to providing Web documentation of the MARC Relator Terms, the Library of Congress provides a representation of the MARC Relator Terms in RDF/XML. Refinements of dc:contributor are, in the RDF/XML representation, asserted to be sub-properties of dc:contributor. In RDF/XML, this is done as follows:

<rdf:Description rdf:about="">
rdf:resource="" />

In determining whether a sub-property relationship was to be asserted, LC and the Usage Board took a fairly narrow view. The relationship was asserted only if the contribution was judged to apply, by its nature, to the content of the resource. For example, whether or not "binder" is to be considered a sub-property of dc:contributor depends on the nature of the resource. Where the resource in question is valued as an art object, a binder may be construed as a "contributor" to its content; in other cases, the binder may not have this role.

Roles as refinements of Dublin Core elements

A subset of MARC Relator Terms have been identified as refinements of dc:contributor. The MARC Relator term marcrel:CRE (Creator) is asserted to be a sub-property of both dc:creator and dc:contributor. In a few cases, MARC Relator terms are considered to be refinements of Dublin Core elements other than dc:contributor. The MARC Relator terms marcrel:PBL (Publisher) and marcrel:DST (Distributor) are considered refinements of dc:publisher, as a publisher may or may not also be a "contributor" to the resource. The term marcrel:DPC (Depicted) is considered a sub-property of dc:subject.

Because roles are generally used with dc:contributor, appropriate "Dumb Down" of most agent refinements in the MARC Relator subset will be to dc:contributor, with exceptions noted above. Implementors may choose to describe "creators" using either marcrel:CRE (which will dumb down both to dc:creator and dc:contributor) or dc:creator (which will remain distinct from dc:contributor in Simple Dublin Core).

A document with further examples of refinement relationships and Dumb Down, along with examples of usage in XML, XHTML and RDF/XML, can be found at:

Terms Not on the MARC Relators List

The MARC Relator list has been developed over many years to meet a wide variety of needs. New terms are added on the basis of need, and LC has expressed willingness to continue to expand the list upon request. Implementers also have the option to create and expose alternative vocabularies for the expression of other kinds of roles not reflected in the MARC Relator list.

For those implementations wishing to use terms from the MARC relators list that do not have a sub-property relationship to Dublin Core elements, it should be noted that an implementation may use such terms with no intrinsic harm to interoperability by using them directly, as elements, in their metadata. In the context of a Dublin Core record based on an application profile using MARC relator terms, roles not on the list as valid sub-properties endorsed by DCMI could be used in a Qualified DC expression, but not in a Simple DC expression.

Managing the Use of Role in an Implementation

The full MARC Relator list includes approximately 150 separate terms for various roles. A subset includes sub-property relationships with DC elements endorsed by DCMI. Even within this subset some of the relator terms on the list were created for specific domains and would be of little use in other communities. It might therefore be useful for implementations to declare a further subset of the relator vocabulary as relevant to their specific goals, preferably by way of a formal application profile.

The full list of MARC Relator Terms (including refinements of Dublin Core elements):

The subset of MARC Relator Terms which refine Dublin Core terms:

The RDF representation of MARC Relator Terms:

For further information, see "MARC Relator Terms and Dublin Core"

2005-01-16, Errata: broken link repaired.