#acl AndyPowell:read,write,delete,admin PeteJohnston:read,write,delete,admin All:read = Expressing Dublin Core metadata using XML (DC-XML-Full) = This document is part of the [wiki:Self:. DC Architecture Wiki]. '''IMPORTANT:''' Do '''not''' cite materials in this Wiki other than for the purposes of collaborating on document creation. This Wiki is intended to be used to work on draft copies of documents. Finished documents will be published, in a persistent and citable form, on the dublincore.org Web site (or elsewhere in some cases). || '''Title:''' || '''Expressing Dublin Core metadata using XML (DC-XML-Full)''' || || '''Creator:''' || Pete Johnston, Eduserv Foundation || || '''Creator:''' || Andy Powell, Eduserv Foundation || || '''Date Issued:''' || 2006-09-18 || || '''Identifier:''' || http://dublincore.org/architecturewiki/DCXMLRevision/DCXMLFGuidelines/2006-09-18 || || '''Replaces:''' || Not applicable || || '''Is Replaced By:''' || http://dublincore.org/architecturewiki/DCXMLRevision/DCXMLFGuidelines/2007-06-19 || || '''Latest Version:''' || http://dublincore.org/architecturewiki/DCXMLRevision/DCXMLFGuidelines || || '''Description of Document:''' || This document specifies an XML format for representing a Dublin Core metadata description set. It supports all the features of the description set described by the DCMI Abstract Model. The XML format is known as "DC-XML-Full".|| == Contents == 1. Introduction 1. The DCMI Abstract Model and DC-XML-Full 1. The DC-XML-Full Syntax 1. GRDDL 1. Appendix A: Text Representation of Examples 1. Notes 1. References == 1. Introduction == This document specifies an XML format for representing a DC metadata ''description set''. The XML format is known as "DC-XML-Full". The DCMI Abstract Model [[#DCAM DCAM]] describes the constructs that make up a DC metadata ''description set''. In order to represent a DC metadata description set in an XML document those constructs have to be represented as components in that XML document, i.e. as XML elements and XML attributes, XML element names and XML attribute names, and as XML element content and XML attribute values. === 1.1 Design Considerations === The DC-XML-Full format described in this document was developed using the following design considerations: * The format should provide a serialisation of all the features of the "Description Model" of the DCAM, i.e. it should be possible to represent all the constructs that make up a DC metadata ''description set''. (See [#Note1 Note 1]). * The format is not required to address the features of the "Schema Model" of the DCAM. For example, it is not required to express subproperty relationships between properties, subclass relationships between classes, etc. * The format should be easily usable with XML-based specifications such as XPath, XPointer and XQuery, i.e. for each construct in the DCAM there should be a mapping to exactly one construct in the XML syntax. * The format should not be dependent on features of a single XML Schema language. * It should be possible to describe the format using W3C XML Schema [[#XMLSCHEMA XMLSCHEMA]], but it is not a requirement that when the format is used to serialise ''description sets'' conforming to a DC Application Profile, all the constraints expressed in a DC Application Profile are captured using W3C XML Schema. == 2. The DCMI Abstract Model and DC-XML-Full == According to the DCAM description model: * a ''description set'' is made up of one or more ''descriptions'' * a ''description'' is made up of * zero or one ''resource URI'' and * one or more ''statements'' * a ''statement'' is made up of * exactly one ''property URI'' and * zero or one ''reference to'' a value in the form of a ''value URI'' * zero or more ''representations of'' a value, each in the form of a ''value representation'' * zero or one ''vocabulary encoding scheme URI'' * zero or one ''value class URI'' * a ''value representation'' is either * a ''value string'' or * a ''rich representation'' * a ''value string'' may be associated with either a ''value string language'' or a ''syntax encoding scheme URI'' * a ''value'' may be the ''described resource'' of another ''description'' in the ''description set'' The DC-XML-Full format described in this document implements all the features of the DCAM description model. == 3. The DC-XML-Full Syntax == [[Anchor(sec3.1)]] === 3.1 URIs in DC-XML-Full === The DCAM uses Uniform Resource Identifiers (URIs) [[#RFC3896 RFC3896]] to refer both to resources and to metadata terms (''properties'',''classes'','' vocabulary encoding schemes'' and ''syntax encoding schemes''). In DC-XML-Full, those URIs are encoded as XML attribute values. Later sections of this document describe the use of those different XML attributes in detail. The purpose of this section is to make some general points about the representation of these URIs in DC-XML-Full. [[Anchor(sec3.1.1)]] ==== 3.1.1 URI references ==== In DC-XML-Full, URIs may be encoded as URI references, used as XML attribute values. A URI reference is either a URI or a relative reference [[#RFC3896 RFC3896]]. The URI may be represented in full. The following example shows a URI as the value of the `dcxf:propertyURI` attribute: {{{ DCMI Home Page }}} '''XML Example 1: URI as attribute value''' The representation of the URI may be abbreviated through the use of an XML entity reference as follows, for example: {{{ ]> DCMI Home Page }}} '''XML Example 2: URI as attribute value (with XML entity reference)''' For all of the attributes in DC-XML-Full which have URIs as values, the value may also be a relative reference. The relative reference is resolved relative to a base URI, obtained either from the value of an `xml:base` attribute or from the URI of the document itself. In the following example, the value of the `dcxf:propertyURI` attribute is a relative reference. It is resolved relative to the base URI provided by the `xml:base` attribute to obtain a target URI of `http://purl.org/dc/elements/1.1/title`: {{{ DCMI Home Page }}} '''XML Example 3: Relative reference as attribute value''' [[Anchor(sec3.1.2)]] ==== 3.1.2 URIs, DC-XML-Full Qualified Names and Namespace Declarations ==== In DC-XML-Full, URIs may also be represented as DC-XML-Full Qualified Names. A DC-XML-Full Qualified Name is an abbreviation for a URI used in the DC-XML-Full format. A DC-XML-Full Qualified Name consists of an optional "prefix" followed by a hyphen ("-") and a "local name". The form of a DC-XML-Full Qualified Name is: ||[1] ||[[Anchor(QualifiedName)]] !QualifiedName ||::= ||([#Prefix Prefix] '-')? [#LocalName LocalName] || ||[2] ||[[Anchor(Prefix)]] Prefix ||::= ||( [http://www.w3.org/TR/REC-xml#NT-Letter Letter] | [http://www.w3.org/TR/REC-xml#NT-Digit Digit] ) [#NHNameChar NHNameChar]* || ||[3] ||[[Anchor(LocalName)]] !LocalName ||::= ||( [http://www.w3.org/TR/REC-xml#NT-Letter Letter] | [http://www.w3.org/TR/REC-xml#NT-Digit Digit] ) [#NHNameChar NHNameChar]* || ||[4] ||[[Anchor(NHNameChar)]] NH!NameChar ||::= || [http://www.w3.org/TR/REC-xml#NT-Letter Letter] | [http://www.w3.org/TR/REC-xml#NT-Digit Digit] | '.' | ':' | '_' | [http://www.w3.org/TR/REC-xml#NT-CombiningChar CombiningChar] | [http://www.w3.org/TR/REC-xml#NT-Extender Extender] || The "prefix" in a DC-XML-Full Qualified Name is associated with a "namespace URI" using a namespace declaration, made using a Namespace Declaration Element, which occurs near the start of a DC-XML-Full instance (see [#sec3.3 Section 3.3] below). The URI represented by the DC-XML-Full Qualified Name is determined by concatenating the "namespace URI" with which the prefix is associated and the "local name". If the prefix used in a DC-XML-Full Qualified Name has not been associated with a URI in a namespace declaration, it is an error and no URI can be generated for that DC-XML-Full Qualified Name. If the prefix has been associated with multiple URIs (though multiple namespace declarations) then the prefix is associated with the namespace URI specified in the latest declaration in the DC-XML-Full instance. The prefix in a DC-XML-Full Qualified Name is optional. If a prefix is not present, then the "name" is concatenated with the default "namespace URI". The default namespace URI is declared using a namespace declaration with no prefix. If no default "namespace URI" has been declared, and a DC-XML-Full Qualified Name with no prefix is used, it is an error and no URI can be generated for that DC-XML-Full Qualified Name. For a software application that is "encoding" a ''description set'' by generating a DC-XML-Full instance, a DC-XML-Full Qualified Name to represent a URI is determined by * dividing the URI into a pair consisting of a local name (the trailing characters of the URI, subject to the lexical constraints described above) and a namespace URI (the preceding part of the URI), and * providing a Namespace Declaration element for this namespace URI (either using a prefix in the namespace declaration and in the DC-XML-Full Qualified Name, or using a default namespace declaration and omitting the prefix in the DC-XML-Full Qualified Name). Note that this means for a single URI there is more than one possible DC-XML-Full Qualified Name representation. For example, the URI `http://purl.org/dc/elements/1.1/date` might be represented using any of the following (namespace URI, local name) pairs: * `{http://purl.org/dc/elements/1.1/}, title` * `{http://purl.org/dc/elements/1.1/t}, itle` * `{http://purl.org/dc/elements/1.1/ti}, tle` * `{http://purl.org/dc/elements/1.1/tit}, le` * `{http://purl.org/dc/elements/1.1/titl}, e` Communities typically decide on a convention for the DC-XML-Full Qualified Name to be used for a URI, particularly for the URIs of terms (''properties'', ''classes'','' vocabulary encoding schemes'' and ''syntax encoding schemes''), but in theory any of these four forms could be deployed without changing the interpretation of the instance. For all DCMI terms, the convention used by the DCMI community is to split the term URI into an expanded name at the right-most '/' (forward slash) character (as per the first example above). Also, the characters used for the prefix in a DC-XML-Full Qualified Name are not significant, but communities often adopt a convention on the common use of a prefix to facilitate human readability. The following example shows a namespace declaration and the use of a DC-XML-Full Qualified Name for the value of the `dcxf:propertyQualName` attribute: {{{ DCMI Home Page }}} '''XML Example 4: DC-XML-Full Qualified Name as attribute value''' [[Anchor(sec3.2)]] === 3.2 Encoding a Description Set: The Description Set Element === A ''description set'' is a set of one or more ''descriptions''. In DC-XML-Full, a ''description set'' is represented by an XML element known as a Description Set Element (See [#Note2 Note 2]). A DC-XML-Full instance represents a single DC ''description set'', so has exactly one Description Set Element. A Description Set Element has an expanded name (XML Namespace Name/local name pair) with the XML Namespace Name `http://dublincore.org/xml/dc-xml-full/2006/09/18/` and local name `descriptionSet`. In the examples presented in this document, the XML Namespace Name `http://dublincore.org/xml/dc-xml-full/2006/09/18/` is always associated with the prefix "dcxf". For convenience, after this point, the names of XML elements and XML attributes are presented in the text as XML QNames (e.g. `dcxf:descriptionSet`, `dcxf:resourceURI`), rather than as expanded names, but they should be read as XML expanded names: the prefix used is not significant. A Description Set Element contains zero or more Namespace Declaration Elements followed by one or more Description Elements. {{{ DCMI Home Page }}} '''XML Example 5: the Description Set Element''' [[Anchor(sec3.3)]] === 3.3 Namespace Declaration Elements === A namespace declaration associates a URI with a prefix, so that when that prefix is used in a DC-XML-Full Qualified Name, that URI is used as a "namespace URI". A namespace declaration is made using a Namespace Declaration Element. A Namespace Description Element is a child element of a Description Set Element and has the name `dcxf:namespaceDeclaration`. Any Namespace Declaration Elements must occur before the Description Elements in a DC-XML-Full instance. A Namespace Declaration Element must be empty. The namespace declaration must include a namespace URI, represented by the value of the `dcxf:namespaceURI` attribute, and it may include a prefix, represented by the value of the `dcxf:prefix` attribute. If the `dcxf:prefix` attribute attribute is present, the element represents a namespace declaration associating the prefix and the URI. In the following example, declarations are provided for two prefixes, each of which is used subsequently in a DC-XML-Full Qualified Name. {{{ DCMI Home Page }}} '''XML Example 6: The Namespace Declaration Element''' If the `dcxf:prefix` attribute is omitted, then the element represents a default namespace declaration. In the following example, the DC-XML-Full Qualified Name used as the value of the `dcxf:resourceQualName` attribute has no prefix, and the namespace URI from the default namespace declaration is applied. {{{ DCMI Home Page }}} '''XML Example 7: The Namespace Declaration Element''' === 3.4 Encoding a Description: The Description Element === A ''description'' is a set of one or more ''statements'' about a resource. In DC-XML-Full, a ''description'' is represented by an XML element known as a Description Element. A Description Element is a child element of a Description Set Element and has the name `dcxf:description`. The Description Element(s) must follow any Namespace Declaration Elements in a DC-XML-Full instance. A Description Element contains one or more Statement Elements. The following example shows a ''description set'' consisting of a single ''description'': {{{ DCMI Home Page }}} '''XML Example 8: the Description Element''' A ''description set'' may contain multiple ''descriptions''. In DC-XML-Full, each ''description'' is represented by a separate Description Element. The order of the Description Elements within a Description Set Element is not significant. The following example shows a ''description set'' consisting of two ''descriptions'': {{{ DCMI Home Page UKOLN Home Page }}} '''XML Example 9: Multiple Description Elements''' The encoding of ''description sets'' with multiple ''descriptions'' is described further in [#sec3.6 section 3.6]. ==== 3.4.1 The Resource URI ==== A ''description'' may have an associated ''resource URI''. In DC-XML-Full, a ''resource URI'' may be encoded in full or may be represented as a DC-XML-Full Qualified Name. In both cases it is represented as the value of an XML attribute of the Statement Element. If the ''resource URI'' appears in full, the attribute has the name `dcxf:resourceeURI`. If the ''resource URI'' is represented using an DC-XML-Full Qualified Name, the attribute has the name `dcxf:resourceQualName`. The examples below show a ''description'' with the ''resource URI'' `http://dublincore.org/pages/home`. {{{ DCMI Home Page }}} '''XML Example 10: the Resource URI Attribute''' Note that the representation of the ''resource URI'' may be abbreviated through the use of an XML entity reference or a URI relative reference (see [#sec3.1.1 Section 3.1.1]). Where a DC-XML-Full Qualified Name is used to represent the URI, the ''resource URI'' is determined from the DC-XML-Full Qualified Name by applying the mapping described in [#sec3.1.2 section 3.1.2]. {{{ DCMI Home Page }}} '''XML Example 11: The Resource Qual Name Attribute''' Note that the examples above illustrate alternate ways of representing the same information. A single Description Element should not have both a `dcxf:resourceURI` and a `dcxf:resourceQualName` attribute. === 3.4 Encoding Statements: Statement Elements === A ''description'' is made up of one or more ''statements''. In DC-XML-Full, each child XML element of a Description Element represents a single ''statement'' and is known as a Statement Element. A Statement Element always has the name `dcxf:statement`. The following example shows a ''description'' consisting of a single ''statement'': {{{ DCMI Home Page }}} '''XML Example 12: A Statement Element''' A ''description'' may be made up of multiple ''statements'', each represented by a separate Statement Element. The order of the Statement Elements within a Description Element is not significant. The following example shows a ''description'' consisting of two ''statements'': {{{ DCMI Home Page Dublin Core Metadata Initiative }}} '''XML Example 13: Multiple Statement Elements''' ==== 3.4.1 The Property URI ==== A ''statement'' must contain exactly one ''property URI''. In DC-XML-Full, a ''property URI'' may be encoded in full or may be represented as a DC-XML-Full Qualified Name. In both cases it is represented as the value of an XML attribute of the Statement Element. If the ''property URI'' appears in full, the attribute has the name `dcxf:propertyURI`. If the ''property URI'' is represented using an DC-XML-Full Qualified Name, the attribute has the name `dcxf:propertyQualName`. The examples below show a ''description'' consisting of two ''statements'' where the ''property URIs'' are `http://purl.org/dc/elements/1.1/title` and `http://purl.org/dc/elements/1.1/publisher`. {{{ DCMI Home Page Dublin Core Metadata Initiative }}} '''XML Example 14: The Property URI Attribute''' Note that the representation of the ''property URI'' may be abbreviated through the use of an XML entity reference or a URI relative reference (see [#sec3.1.1 Section 3.1.1]). Where a DC-XML-Full Qualified Name is used to represent the URI, the ''property URI'' is determined from the DC-XML-Full Qualified Name by applying the mapping described in [#sec3.1.2 section 3.1.2]. {{{ DCMI Home Page Dublin Core Metadata Initiative }}} '''XML Example 15: The Property Qual Name Attribute''' Note that the examples above illustrate alternate ways of representing the same information. A single Statement Element should not have both a `dcxf:propertyURI` and a `dcxf:propertyQualName` attribute. ==== 3.4.2 The Value URI ==== A ''statement'' may contain a ''value URI''. In DC-XML-Full, a ''value URI'' may be encoded in full or may be represented as a DC-XML-Full Qualified Name. In both cases it is represented as the value of an XML attribute of the Statement Element. If the ''value URI'' appears in full, the attribute has the name `dcxf:valueURI`. If the ''value URI'' is represented using an DC-XML-Full Qualified Name, the attribute has the name `dcxf:valueQualName`. The examples below show a ''description'' consisting of two ''statements'' where the second ''statement'' includes the ''value URI'' `http://example.org/agents/DCMI`. {{{ DCMI Home Page Dublin Core Metadata Initiative }}} '''XML Example 16: The Value URI Attribute''' The representation of the ''value URI'' may be abbreviated through the use of an XML entity reference or a URI relative reference (see [#sec3.1.1 Section 3.1.1]). Where a DC-XML-Full Qualified Name is used to represent the URI, the ''value URI'' is determined from the DC-XML-Full Qualified Name by applying the mapping described in [#sec3.1.2 section 3.1.2]. {{{ DCMI Home Page Dublin Core Metadata Initiative }}} '''XML Example 17: The Value Qual Name Attribute''' Note that the examples above illustrate alternate ways of representing the same information. A single Statement Element should not have both a `dcxf:valueURI` and a `dcxf:valueQualName` attribute. ==== 3.4.3 The Vocabulary Encoding Scheme URI Attribute ==== A ''statement'' may include a ''vocabulary encoding scheme URI''. In DC-XML-Full, a ''vocabulary encoding scheme URI'' may be encoded in full or may be represented as a DC-XML-Full Qualified Name. In both cases it is represented as the value of an XML attribute of the Statement Element. If the ''vocabulary encoding scheme URI'' appears in full, the attribute has the name `dcxf:vocabEncSchemeURI`. If the ''vocabulary encoding scheme URI'' is represented using an DC-XML-Full Qualified Name, the attribute has the name `dcxf:vocabEncSchemeQualName`. The examples below show a ''description'' consisting of three ''statements'' where the third ''statement'' includes the ''vocabulary encoding scheme URI'' `http://purl.org/dc/terms/LCSH`. {{{ DCMI Home Page Dublin Core Metadata Initiative Metadata }}} '''XML Example 18: The Vocabulary Encoding Scheme URI Attribute''' Note that the representation of the ''vocabulary encoding scheme URI'' may be abbreviated through the use of an XML entity reference or a URI relative reference (see [#sec3.1.1 Section 3.1.1]). Where a DC-XML-Full Qualified Name is used to represent the URI, the ''vocabulary encoding scheme URI'' is determined from the DC-XML-Full Qualified Name by applying the mapping described in [#sec3.1.2 section 3.1.2]. {{{ DCMI Home Page Dublin Core Metadata Initiative Metadata }}} '''XML Example 19: the Vocabulary Encoding Scheme Qual Name Attribute''' Note that the examples above illustrate alternate ways of representing the same information. A single Statement Element should not have both a `dcxf:vocabEncSchemeURI` and a `dcxf:vocabEncSchemeQualName` attribute. ==== 3.4.4 The Value Class URI Attribute ==== A ''statement'' may include a ''value class URI''. In DC-XML-Full, a ''value class URI'' may be encoded in full or may be represented as a DC-XML-Full Qualified Name. In both cases it is represented as the value of an XML attribute of the Statement Element. If the ''value class URI'' appears in full, the attribute has the name `dcxf:valueClassURI`. If the ''value class URI'' is represented using an DC-XML-Full Qualified Name, the attribute has the name `dcxf:valueClassQualName`. The examples below show a ''description'' consisting of three ''statements'' where the third ''statement'' includes the ''value class URI'' `http://purl.org/dc/terms/LCSH`. {{{ DCMI Home Page Dublin Core Metadata Initiative Metadata }}} '''XML Example 20: The Value Class URI Attribute''' Note that the representation of the ''value class URI'' may be abbreviated through the use of an XML entity reference or a URI relative reference (see [#sec3.1.1 Section 3.1.1]). Where a DC-XML-Full Qualified Name is used to represent the URI, the ''value class URI'' is determined from the DC-XML-Full Qualified Name by applying the mapping described in [#sec3.1.2 section 3.1.2]. {{{ DCMI Home Page Dublin Core Metadata Initiative Metadata }}} '''XML Example 21: the Value Class Qual Name Attribute''' Note that the examples above illustrate alternate ways of representing the same information. A single Statement Element should not have both a `dcxf:vocabEncSchemeURI` and a `dcxf:vocabEncSchemeQualName` attribute. ==== 3.4.5 Empty Statement Elements ==== The presence of a ''value representation'' in a ''statement'' is optional. In DC-XML-Full, the Statement Element may therefore be empty. The example below shows a ''description'' consisting of four ''statements'' where the fourth ''statement'' provides a ''value URI'' but no ''value representation''. {{{ DCMI Home Page Dublin Core Metadata Initiative Metadata }}} '''XML Example 22: Empty Statement Element''' === 3.5 Encoding Value Strings and Rich Representations: Value Representation Elements === A ''statement'' may contain multiple ''value representations''. In DC-XML-Full, the ''value representations'' are represented by child elements of the Statement Element known as Value Representation Elements. The order of the Value Representation Elements within a Statement Element is not significant. A value representation may take the form of a ''value string'' or a ''rich representation'' ==== 3.5.1 The Value String ==== A ''value string'' is represented by an XML element with the element name `dcxf:valueString`. The example below shows a ''description'' consisting of four ''statements'' where the first three ''statements'' each include a ''value string''. {{{ DCMI Home Page Dublin Core Metadata Initiative Metadata }}} '''XML Example 23: The Value String''' A ''statement'' may contain multiple ''value strings'', each represented by a separate `dcxf:valueString` child XML element. The following example shows a ''description'' in which the first ''statement'' provides three ''value strings'': {{{ Site Map Plan du site Plan del sitio Dublin Core Metadata Initiative }}} '''XML Example 24: Multiple Value Strings''' ===== 3.5.1.1 The Value String Language ===== A ''value string'' may have an associated ''value string language''. In DC-XML-Full, a ''value string language'' is represented by an `xml:lang` attribute of the `dcxf:valueString` XML element representing the ''value string''. The example below shows a ''description'' consisting of three ''statements'' where the first ''statement'' has an associated ''value string language'' "en-GB" with the ''value string'' "DCMI Home Page": {{{ DCMI Home Page Dublin Core Metadata Initiative 2005-05-05 }}} '''XML Example 25: The Value String Language''' ===== 3.5.1.2 The Syntax Encoding Scheme URI ===== A ''value string'' may have an associated ''syntax encoding scheme URI''. In DC-XML-Full, a ''syntax encoding scheme URI'' may be encoded in full or may be represented as a DC-XML-Full Qualified Name. In both cases it is represented as the value of an XML attribute of the Statement Element. If the ''syntax encoding scheme URI'' appears in full, the attribute has the name `dcxf:syntaxEncSchemeURI`. If the ''syntax encoding scheme URI'' is represented using an DC-XML-Full Qualified Name, the attribute has the name `dcxf:syntaxEncSchemeQualName`. The examples below show a ''description'' consisting of three ''statements'' where the third ''statement'' associates the ''syntax encoding scheme URI'' `http://www.w3.org/2001/XMLSchema#date` with the ''value string'' "2005-05-05": {{{ DCMI Home Page Dublin Core Metadata Initiative 2005-05-05 }}} '''XML Example 26: The Syntax Encoding Scheme URI Attribute''' Note that the representation of the ''syntax encoding scheme URI'' may be abbreviated through the use of an XML entity reference or a URI relative reference (see [#sec3.1.1 Section 3.1.1]). Where a DC-XML-Full Qualified Name is used to represent the URI, the ''syntax encoding scheme URI'' is determined from the DC-XML-Full Qualified Name by applying the mapping described in [#sec3.1.2 section 3.1.2]. {{{ DCMI Home Page Dublin Core Metadata Initiative 2005-05-05 }}} '''XML Example 27: the Syntax Encoding Scheme Qual Name Attribute''' Note that the examples above illustrate alternate ways of representing the same information. A single `dcxf:valueString` XML element should not have both a `dcxf:syntaxEncSchemeURI` and a `dcxf:syntaxEncSchemeQualName` attribute. ==== 3.5.2 Rich Representations ==== A ''value'' may also be represented by a ''rich representation'' - i.e. by some XML data or by a binary data object. ===== 3.5.2.1 XML Data ===== An XML data ''rich representation'' may be provided in two ways. It may be provided "inline" within the DC-XML-Full document or it may be provided as a separate XML document, the URI of which is provided as an attribute value. Inline XML data is represented by the content of a Value Representation Element with the element name `dcxf:XMLRepresentation`. The example below shows a ''description'' consisting of two ''statements'' where the second ''statement'' includes a ''rich representation'' of the ''value'' in the form of an XML fragment: {{{ DCMI Home Page

The DCMI home page provides an overview of the content of the DCMI Web site. It also displays current news items.

 }}} '''XML Example 28: Rich Representation - XML Data''' The URI of external XML data is encoded as the value of the `dcxf:representationURI` attribute of the `dcxf:XMLRepresentation` element, as follows: {{{ DCMI Home Page }}} '''XML Example 29: Rich Representation - XML Data''' ===== 3.5.2.2 Binary Data ===== A binary data ''rich representation'' may be provided in two ways. It may be provided "inline" within the DC-XML-Full document or it may be provided as a separate resource, the URI of which is provided as an attribute value. Inline binary data is represented by the content of a Value Representation Element with the element name `dcxf:binaryRepresentation`. The XML element content is a Base64 encoding of the binary object. The example below shows a ''description'' consisting of two ''statements'' where the second ''statement'' includes a ''rich representation'' of the ''value'' in the form of a binary data object: {{{ DCMI Home Page AABBCCDDEEFF }}} '''XML Example 30: Rich Representation - Binary Data''' The URI of external binary data is encoded as the value of the `dcxf:representationURI` attribute of the `dcxf:binaryRepresentation` element: {{{ DCMI Home Page }}} '''XML Example 31: Rich Representation - Binary Data''' A ''statement'' may contain multiple ''rich representations'' in the form of separate `dcxf:XMLRepresentation` or `dcxf:binaryRepresentation` XML elements. Furthermore, a single ''statement'' may provide both ''value strings'' and ''rich representations''. The following example shows a ''description'' in which the second ''statement'' provides two ''value strings'' and two ''rich representations'': {{{ DCMI Home Page The home page provides an overview of the content of the DCMI Web site. It also displays current news items. El Home Page proporciona una descripción del contenido del sitio del Web de DCMI. Además presenta noticias actuales.

The home page provides an overview of the content of the DCMI Web site. It also displays current news items.

El Home Page proporciona una descripción del contenido del sitio del Web de DCMI. Además se presentan noticias actuales.

 }}} '''XML Example 32: Multiple Value Strings and Multiple Rich Representations''' [[Anchor(sec3.6)]] === 3.6 Encoding Descriptions of Values === As noted in [#sec3.3 section 3.3], ''description sets'' may contain multiple ''descriptions''. Each ''description'' is represented by a separate Description Element. The order of the Description Elements has no significance. It may be that the ''described resource'' of a ''description'' is the ''value'' of a ''statement'' in another ''description'' within the ''description set''. If that resource has been assigned a URI, then that URI appears as the ''value URI'' in the ''statement'' where the resource is the ''value'' and as a ''resource URI'' in the ''description'' of that resource, as shown below: {{{ DCMI Home Page DCMI Alternative Home Page Dublin Core Metadata Initiative }}} '''XML Example 33: Value as Described Resource''' In some cases the resource will not have a URI assigned, or the URI will not be known. Such a resource may still be a ''value'' in a ''statement'' and the ''described resource'' of another ''description'' in the same ''description set''. In such cases, the association between the ''statement'' and the second ''description'' is made by labelling the second ''description'' using an XML attribute of the Description Element. The attribute has the name `dcxf:descriptionId`. The attribute value may then be cited in the the value of a `dcxf:descriptionRef` XML attribute of one or more Statement Elements elsewhere in the same ''description set''. Each value of a `dcxf:descriptionRef` XML attribute must match the value of a `dcxf:descriptionId` attribute in the same DC-XML-Full instance. Note that this is a syntactic mechanism for linking references to ''values'' in ''statements'' to the ''descriptions'' of those ''values'': the label itself does not appear in the ''description set''. {{{ DCMI Home Page DCMI Alternative Home Page Dublin Core Metadata Initiative }}} '''XML Example 34: Value as Described Resource''' == 4. GRDDL == An XSLT transformation from DC-XML-Full to RDF/XML [[#RDFXML RDFXML]] is available. The GRDDL specification [[#GRDDL GRDDL]] defines a set of conventions for associating an XML instance document with a transformation. One approach is to reference the transformation using an attribute of the root element, as follows: {{{ ... }}} '''XML Example 35: GRDDL''' The transformation can also be associated with a set of XML documents through information provided by the "namespace document". == Appendix A. DC-TEXT Representation of Examples == This appendix provides representations of all the examples provided in the main body of the document using the DC-Text syntax [[#DC-TEXT DC-TEXT]]. (to be completed) == Notes == [[Anchor(Note1)]]'''[1]''' This document defines one XML format for representing DC metadata description sets in XML. Other formats may exist supporting other subsets of the DCMI Abstract Model. For example, the Open Archives Initiative Protocol for Metadata Harvesting [[#OAIPMH OAIPMH]] defines a format, commonly known as oai_dc, which supports the serialisation only of description sets containing a single description, with statements referencing only the fifteen properties of the DCMES, and using value strings only. oai_dc is a different XML format from DC-XML-Full, but that does not change the value and usefulness of oai_dc as a format for serialising that particular subset of DC metadata description sets. [[Anchor(Note2)]]'''[2]''' In this document the term "element" is used to refer only to XML elements, and it should always be interpreted in that sense wherever it occurs. It is not used to refer to the properties of the DCMES. == References == [[Anchor(DCAM)]]'''[DCAM]'''[[BR]]DCMI Abstract Model[[BR]]http://dublincore.org/documents/abstract-model/ [[Anchor(XML)]]'''[XML]'''[[BR]]''Extensible Markup Language (XML) 1.0 (Third Edition)''. W3C Recommendation 04 February 2004.[[BR]]http://www.w3.org/TR/REC-xml [[Anchor(XMLSCHEMA)]]'''[XMLSCHEMA]'''[[BR]]''XML Schema Part 0: Primer Second Edition''. W3C Recommendation 28 October 2004.[[BR]]http://www.w3.org/TR/xmlschema-0/ [[Anchor(RFC3986)]]'''[RFC3986]'''[[BR]]''Uniform Resource Identifier (URI): Generic Syntax''.[[BR]]http://www.ietf.org/rfc/rfc3986.txt [[Anchor(RDFXML)]]'''[RDFXML]'''[[BR]]''RDF/XML Syntax Specification (Revised)'' W3C Recommendation 10 February 2004.[[BR]]http://www.w3.org/TR/rdf-syntax-grammar/ [[Anchor(GRDDL)]]'''[GRDDL]'''[[BR]]''Gleaning Resource Descriptions from Dialects of Languages (GRDDL)'' W3C Team Submission 16 May 2005[[BR]]http://www.w3.org/TeamSubmission/grddl/ [[Anchor(OAIPMH)]]'''[OAIPMH]'''[[BR]]''The Open Archives Initiative Protocol for Metadata Harvesting'' Protocol Version 2.0 of 2002-06-14.[[BR]]http://www.openarchives.org/OAI/openarchivesprotocol.html [[Anchor(DC-TEXT)]]'''[DC-TEXT]'''[[BR]]''DC-Text: A Text Syntax for Dublin Core Metadata'' Draft of 2006-09-18.[[BR]]http://dublincore.org/architecturewiki/DCText/2006-09-18 == Changes in this version == * Rename format to DC-XML-Full * Change dcx prefix to dcxf and XML namespace name to http://dublincore.org/xml/dc-xml-full/2006/09/18/ * Introduce concept of Value Class URI and dcxf:valueClassURI and dcxf:valueClassQualName attributes * Modify references to related descriptions