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Dublin Core
Dublin Core could be the most famous Metadata
standard today. From its first workshop held in 1995,
there have been eight Metadata workshops so far and resulted
in the current Dublin Core Metadata Element Set (DCMES).
The Dublin Core Metadata
Initiative is the formal forum responsible for the
DCMES, and is "dedicated to promoting the widespread
adoption of interoperable metadata standards and developing
specialized metadata vocabularies for describing resources
that enable more intelligent information discovery systems".
The DCMES was designed as the descriptive
metadata to support resource discovery. As DCMI director
Stuart L. Weibel mentioned,
the mission of the DCMI is to make it easier to find resources
using the Internet through the following activities:
- Developing metadata standards for discovery
across domains;
- Defining frameworks for the interoperation of metadata
sets;
- Facilitating the development of community or discipline-specific
metadata sets that work within the frameworks of cross-domain
discovery and metadata interoperability.
By now the current version of DCMES (Version
1.1) contains fifteen
elements separated into three groups: Content, Intellectual
Property, and Instantiation. These elements could be further
refined by qualifiers. A qualifier gives additional information
on the values of an element, such as classification or
controlled vocabulary or other encoding schemes used,
to define or narrow down the meaning of element values
in the specific project. A list
of qualifiers is recommended within DCMES.
From the beginning of DCMI, the Dublin Core
has been heavily influenced by librarians, and seen by
them that DC has the similar functions as MARC to organize
electronic resources. But DC is not intended to replace
those rich and complicated description standards. Instead,
it provides a simple core set of description elements
that can be used by normal users who are not familiar
with cataloging rules for simple digital resource description.
In September 2001, Dublin Core Metadata
Element Set was approved by National Information Standard
Organization as an American National Standard ANSI/NISO
Z39.85. Besides that, Dublin Core 1.1 has been adopted
by CEN/ISSS (European Committee for Standardization /Information
Society Standardization System) as part of a CEN/ISS Workshop
Agreement (CWA 13874)
The three features of Metadata identified
by Vellucci as the
new buzzwords in digital information organization: flexibility,
interoperability, and extensibility are also reflected
in DCMES:
Flexibility
It's a core set of simple elements that could be applied
for general digital resources in many domains. All the
elements are optional and repeatable. Although each DC
element or qualifier would follow a simple structure,
there is no formal syntax defined for DC itself. It only
deploys W3C's RDF as its application module. The Metadata
records could have as many descriptive elements as needed
to ensure each entity within the digital collection could
be uniquely identified.
Interoperability
There are great demands for embedding more than one Metadata
element set in the resource repository. RDF allows a group
of different metadata sets to be described by implementing
registry within the
application. Through registry, the structure and semantics
of each Metadata set will be defined, and the way they
are recorded and accessed will be described. It will enhance
the interoperability of Metadata sets co-exist inside
the application and improve the search and exchange ability.
Extensibility
The schema could be modified and extended by choosing
part of DC elements set and adding new elements and qualifiers
according to the specific requirement of the project within
the framework, as long as the creators follow the DCMI
Recommendations of schema. This encourages the extension
of DCMES application in different domains.
The DCMI Website maintains a comprehensive
list of Dublin
Core projects around the world, and there are several
DCMI work group are studying the particular DC schema
for different domains, such as Education, Government,
Libraries Working Group and several Special Interest Groups.
This also could improve the awareness of DC in most disciplines,
prevent duplication by individual project, and enhance
interoperability of different applications under DC schema.
Mainly the DCMES focuses on the description
of digital resources. Because of its simplicity, it pays
little attention on the resource's intellectual property
or access rights management. Although the simplicity could
enhance interoperability, it does not accommodate the
semantic and functional richness supported by complex
information retrieval standard (Z39.85). Combination of
richer metadata schemes with Dublin Core is recommended by
NISO, including mapping those richer metadata schemes
to Dublin Core for export or for cross-system searching.
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