6.3.1 The Dublin Core Element Set and the Arts and Humanities Data Service
"The Dublin Core is a 15-element metadata element set intended to facilitate discovery of electronic resources. Originally conceived for author-generated description of web resources, it has also attracted the attention of formal resource description communities such as museums and libraries"
[Dublin Core Metadata home page - http://purl.oclc.org/metadata/dublin_core/]
By the mid-1990's large scale web users, document creators and information providers had recognized the pressing need to introduce some kind of basic cataloguing scheme for documenting resources on the web. The scheme needed to be accessible enough to be adopted and implemented by typical web content creators who had little or no formal cataloguing training. The set of metadata elements needed to be simpler than those used in traditional library cataloguing but which also offered information systems greater precision than the crude indexing methods already employed by unreliable search engines and web crawlers.
The Dublin Core Metadata Element Set grew out of a series of meetings and workshops comprising of experts from the library world, the networking and digital library research community, and content specialists. The basic objectives of the Dublin Core initiative included:
- to produce a core set of descriptive elements which would be capable of describing or identifying the majority of resources available on the internet. Unlike a traditional library where the main focus is on cataloguing published textual materials, the Internet contains a vast range or material in a variety of formats, including non-textual material such as images, video, most of which do have not been 'published' in any formal way.
- to make this scheme intelligible enough that it could be easily utilized by cataloguers but still retain enough content that it functioned effectively as a catalogue record.
- to encourage the adoption of the scheme on an international level by ensuring that it provided the best format for documenting digital objects on the web
The Dublin Core element set provides a straightforward framework for documenting features of a work such as who created the work, what its content is and what languages it contains, where and from whom it is available from and in what formats, and whether it derived from a printed source. At a basic level the element set uses commonly understood terms and semantics which are intelligible to most disciplines and information systems communities. The descriptive terms were chosen to be generic enough to be understood by a document author, but could also be extended to provide full and precise cataloguing information. For example textual authors, painters, photographers, writers of software programs can all be considered 'creators' in a broad sense.
Two main principles apply when creating a Dublin Core record, which are that all elements are optional and all elements are repeatable. Therefore if a work is the result of numerous contributors it is simple to record the details of each member (name, contact details etc) as well as their specific contribution (author, editor, photographer, etc) by simply repeating the appropriate element. These basic details can be extended by the use of qualifiers such a scheme, type, and language on the elements. The <i>scheme qualifier identifies a recognized coding or cataloguing scheme used in a Dublin Core element, for example if a document employs an established cataloguing scheme such as the Library of Congress subject headings. The use of the <I>scheme qualifier provides a mechanism to introduce a degree of standardization and consistency to the format. The <i>type qualifier refines more precisely he content of a single element, for example the <i>author element is often used several times for the same individual. The <I>type qualifier can be employed to differentiate details such as the authors postal address, email address, telephone number, etc. The <i>language element simply identifies the language of the element value.
Implementing the Dublin Core
The Dublin Core element set was designed for documenting web resources and it is easily integrated into web pages using the HTML <META> tag, inserted between the ... tags and before the of the work. No specialist tools more sophisticated than an average word processor are required to produce the content of a Dublin Core record, however a number of labour saving devices are available, notably the DC-dot generator available from the UKOLN web site [http://www.ukoln.ac.uk/metadata/dcdot/]. The DC-dot will automatically generate the <META> tags for any web site, which can be easily edited and extended further.
Conclusions and further reading
The Dublin Core element scheme offers enormous potential as a useable standard cataloguing procedure for digital resources on the web. The core set of elements are broad and encompassing enough to be of use to novice web authors and skilled cataloguers alike. However its success will ultimately be dependent on its wide-scale adoption by the internet community as a whole. It is also crucial that the rules of the scheme be implemented in an intelligent and systematic way. To fulfil this objective more has to be done to refine and stabalize the element set. The provision of simple Dublin Core generating tools, which demonstrate the benefits of including metadata, must become more prevalent.
The Arts and Humanities Data Service (AHDS), in association with the UK office for Library and Information Networking (UKOLN), has produced a publication which outlines in more detail the best practices involved in using Dublin Core, as well as giving many practical examples. "Discovering Online Resources across the Humanities: A practical implementation of the Dublin Core" (ISBN 0-9516856-4-3). This is available also freely available from the AHDS web site, [http://ahds.ac.uk/]
As a practical illustration of how the Dublin Core element set can be implemented in order to perform searches for individual items across disparate collections is the AHDS Gateway [http://ahds.ac.uk:8080/ahds_live/]. The AHDS Gateway is, in reality, an integrated catalogue of the holdings of the five individual Service Providers, which make up the AHDS. Although the Service Providers are separated geographically, by providing Dublin Core records describing each of their holdings, users can very simply search across the complete holdings of the AHDS from one single access point.
The Dublin Core Elements
This set of official definitions of the Dublin Core metadata element set can be found at: http://purl.oclc.org/metadata/dublin_core_elements
Element Descriptions
1.Title
Label: TITLE
The name given to the resource by the CREATOR or PUBLISHER. Where possible standard authority files should be consulted when entering the content of this element. For example the Library of Congress or British Library title lists can be used, but always remember to indicate the source using the 'scheme' qualifier.
2.Author or Creator
Label: CREATOR
The person or organization primarily responsible for creating the intellectual content of the resource. For example, authors in the case of written documents, artists, photographers, or illustrators in the case of visual resources. Note that this element does not refer to the person who is responsible for digitizing a work, this belongs in the CONTRIBUTOR element. So in the case of a machine- readable version of King Lear held by the OTA, the CREATOR remains William Shakespeare, and not the person who transcribed it into digital form. Again, standard authority files should be consulted for the content of this element.
3.Subject and Keywords
Label: SUBJECT
The topic of the resource. Typically, subject will be expressed as keywords or phrases that describe the subject or content of the resource. The use of controlled vocabularies and formal classification schemas is encouraged.
4.Description
Label: DESCRIPTION
A textual description of the content of the resource, including abstracts in the case of document-like objects or content descriptions in the case of visual resources.
5.Publisher
Label: PUBLISHER
The entity responsible for making the resource available in its present form, such as a publishing house, a university department, or a corporate entity.
6.Other Contributor
Label: CONTRIBUTOR
A person or organization not specified in a CREATOR element who has made significant intellectual contributions to the resource but whose contribution is secondary to any person or organization specified in a CREATOR element (for example, editor, transcriber, and illustrator).
7.Date
Label: DATE
The date the resource was made available in its present form. Recommended best practice is an 8 digit number in the form YYYY-MM-DD as defined in http://www.w3.org/TR/NOTE-datetime, a profile of ISO 8601. In this scheme, the date element 1994-11-05 corresponds to November 5, 1994. Many other schema are possible, but if used, they should be identified in an unambiguous manner.
8.Resource Type
Label: TYPE
The category of the resource, such as home page, novel, poem, working paper, technical report, essay, dictionary. For the sake of interoperability, TYPE should be selected from an enumerated list that is under development in the workshop series at the time of publication of this document. See
http://sunsite.berkeley.edu/Metadata/types.html for current thinking on the application of this element
9.Format
Label: FORMAT
The data format of the resource, used to identify the software and possibly hardware that might be needed to display or operate the resource. For the sake of interoperability, FORMAT should be selected from an enumerated list that is under development in the workshop series at the time of publication of this document.