Guidelines for implementing Dublin Core™ in XML

1. Introduction

This document provides guidelines for people implementing Dublin Core™ [DCMI] metadata applications using XML [XML]. It considers both simple (unqualified) DC and qualified DC applications. In each case, the underlying metadata model is described (in a syntax neutral way), followed by some specific guidelines for XML implementations. Some guidance on the use of non-DC metadata is also provided.

This document doesnot在dos为编码都柏林核心™提供指导F/XML [RDF]. Nor does it take a position on the relative merits of encoding metadata in 'plain' XML rather than RDF/XML. This document provides guidelines in those cases where RDF/XML is not considered appropriate. Mechanisms for encoding Dublin Core™ metadata in RDF/XML are being developed elsewhere [DCARCH].

2. Terminology

Resource

a resource is anything that has identity. Familiar examples include an electronic document, an image, a service (e.g., "today's weather report for Los Angeles"), and a collection of other resources. Not all resources are network "retrievable"; e.g., human beings, corporations, and bound books in a library can also be considered resources.
 
Property
 
a property is a specific aspect, characteristic, attribute, or relation used to describe a resource.
 
Record
 
a record is some structured metadata about a resource, comprising one or more properties and their associated values.
 

Note that Dublin Core™ metadata elements areproperties(as defined above). Note also that there is potential confusion between the XML usage of the terms 'element' and 'attribute' and the usage of those terms in a more general metadata context.

3. General implementation guidelines

Recommendation 1. Implementors should base their XML applications on XML Schemas [XMLSCHEMA] rather than XML DTDs.Approaches based on XML Schemas are more flexible and are more easily re-used within other XML applications. In some cases it may be sensible to provide both an XML Schema and a DTD for the application. Where XML Schemas are not used, a DTD should be provided instead. The DCMI maintains a list of XML schemas that are in use in projects or products using DCMI metadata [DCXMLS].

Recommendation 2. Implementors should use XML Namespaces [XMLNS] to uniquely identify DC elements, element refinements and encoding schemes.DC namespaces are defined in the DCMI Namespace Recommendation [DCMINS].

Note that it is anticipated thatrecordswill be encoded within one or more container XML element(s) of some kind. This document makes no recommendations for the name of any container element, nor for the namespace that the element should be taken from. Candidate container element names include,,,and.

4. Simple Dublin Core™

4.1 Abstract model

• Asimple DC recordis made up of one or morepropertiesand their associatedvalues.
• 每一个propertyis an attribute of theresourcebeing described.
• 每一个propertymust be one of the 15 DCMES [DCMES] elements.
• Propertiesmay be repeated.
• 每一个valueis a literal string.
• 每一个literal stringvaluemay have an associated language (e.g. en-GB).

Note that there is no formal linkage between asimple DC recordand theresourcebeing described. Such a linkage may be made by encoding the URI of theresourceas thevalue直流标识符的元素,但这是not mandatory.

Note that while thevalueof apropertymay be a URI, there is nothing in the simple DC model that indicates this is the case. At their own risk, implementations may choose to guess whichvaluesare URIs and which are not.

4.2 Implementation guidelines

(Implementors should follow the general guidelines.)

Recommendation 3. Implementors should encodepropertiesas XML elements andvaluesas the content of those elements.The name of the XML element should be an XML qualified name (QName) which associates the element name with the appropriate DCMI namespace name. For example, use

Dublin Core™ in XML

rather than

Recommendation 4. Thepropertynames for the 15 DC elements should be all lower-case.For example, use

Dublin Core™ in XML

rather than

Dublin Core™ in XML

Recommendation 5. Multipleproperty valuesshould be encoded by repeating the XML element for thatproperty.For example:

First title Second title

4.3 Example - a simple DC record

http://example.org/myapp/schema.xsd"xmlns:dc="http://purl.org/dc/elements/1.1/">
< dc: title > UKOLN < / dc:名称> < dc: description > UKOLN is a national focus of expertise in digital information management. It provides policy, research and awareness services to the UK library, information and cultural heritage communities. UKOLN is based at the University of Bath.   UKOLN, University of Bath  http://www.ukoln.ac.uk/

Note that thehttp://example.org/myapp/schema.xsdXML schema does not exist - this is a ficticious example.

5. Qualified Dublin Core™

5.1 Abstract model

• Aqualified DC recordis made up of one or morepropertiesand their associatedvalues.
• 每一个propertyis an attribute of theresourcebeing described.
• 每一个propertymust be either:
  • one of the 15 DC elements,
  • one of the other elements recommended by the DCMI (e.g. audience),
  • one of theelement refinementslisted in the DC Qualifiers recommendation [DCQ].
• Propertiesmay be repeated.
• 每一个valueis a literal string.
• 每一个valuemay have an associatedencoding scheme.
• 每一个encoding schemehas aname.
• 每一个literal stringvaluemay have an associated language (e.g. en-GB).

Note that for encoding schemes currently recommended by the DCMI, the name is specified in the DC Qualifiers recommendation [DCQ] (listed as the 'Name', not the 'Label'). It is anticipated that the DCMI will develop other mechanisms for registering agreed names for schemes in the future.

5.2 Implementation guidelines

(Implementors should follow the general guidelines and the guidelines for simple Dublin Core™.)

Recommendation 6.Element refinementsshould be treated in the same way as otherproperties.The name of the XML element should be an XML qualified name (QName) which associates the element refinement name with the appropriate DCMI namespace name. For example:

2002-06

Element refinements are elements in their own right and are therefore best encoded in a similar way to other DC elements. In particular, it should be noted that element refinements may have further refinements of their own (e.g. 'format' is refined by 'extent' which might be further refined by 'duration').

See also Note 1 below.

Recommendation 7.Encoding schemesshould be implemented using the 'xsi:type' attribute of the XML element for theproperty.The name of the encoding scheme should be given as the attribute value, and should be in the form of an XML qualified name (QName) which associates the scheme name with the appropriate namespace name. For example:

http://www.ukoln.ac.uk/