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A DIDL document consists out of a main Item (the compound object) at least underlying Item containing the bibliographic metadata.
In addition to the bibliographic metadata, the compound object MAY include zero or more so-called objects. Examples of such object are files containing the textual publication, underlying datasets or other supplementary material or a Jump off page - this is a humanreadble webpage containing descriptive information about the bibliografic work, usually generated by the repository software based on the metadata present. The object may also be a reference to an external websource (i.e. a resource not in the custody of the repository).
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<didl:DIDL
xmlns:didl="urn:mpeg:mpeg21:2002:02-DIDL-NS"
xmlns:dii="urn:mpeg:mpeg21:2002:01-DII-NS"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<!-- Compound Object -->
<didl:Item>
<!-- Persistent Identifier - MANDATORY-->
<didl:Descriptor>
(...)
</didl:Descriptor>
<!-- Descriptive Metadata -->
<didl:Item>
(...)
</didl:Item>
<!-- Object File -->
<didl:Item>
(...)
</didl:Item>
<!-- Jump off Page -->
<didl:Item>
(...)
</didl:Item>
</didl:Item>
</didl:DIDL>
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A DIDL Compound Object Item consists out of one descriptors and a number of items. In this case the Descriptor contains a description of a persistent identifier.
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<didl:Item>
<!-- Persistent Identifier for Compound Object Item - MANDATORY-->
<didl:Descriptor>
<didl:Statement mimeType="application/xml">
<dii:Identifier>urn:nbn:ui:99-1234567890</dii:Identifier>
</didl:Statement>
</didl:Descriptor>
<didl:Item>
(...)
</didl:Item>
</didl:Item>
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A DIDL Item consists out of a number of descriptors. A Descriptor contains a descriptions of the digital object referenced in the Component. Examples of such descriptions are persistent identifiers, dates and accessrights. These expressions are included in statements with the 'application/xml' mimetype.
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<didl:Item>
<!-- Persistent Identifier for Object Item - OPTIONAL -->
<didl:Descriptor>
<didl:Statement mimeType="application/xml">
<dii:Identifier>urn:nbn:ui:99-abcdefghijkl</dii:Identifier>
</didl:Statement>
</didl:Descriptor>
<!-- Semantic Type -->
<didl:Descriptor>
<didl:Statement mimeType="application/xml">
<rdf:type rdf:resource="info:eu-repo/semantics/DescriptiveMetadata"/>
</didl:Statement>
</didl:Descriptor>
<!-- Modification Date -->
<didl:Descriptor>
<didl:Statement mimeType="application/xml">
<dcterms:modified>2010-12-14T14:22:48</dcterms:modified>
</didl:Statement>
</didl:Descriptor>
<!-- Access Rights-->
<didl:Descriptor>
<didl:Statement mimeType="application/xml">
<dcterms:AccessRights>http://purl.org/eprints/accessRights/ OpenAccess</dcterms:AccessRights>
</didl:Statement>
</didl:Descriptor>
<!-- Content -->
<didl:Component>
<didl:Resource mimetype="application/xml">
(...)
</didl:Resource>
</didl:Component>
</didl:Item>
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Persistent identifiers are durable, lasting formal identification numbers through which a partical piece of information such as publications, datasets or software may be retrieved, even when they have moved from their original location.
There are various persistent identifier solutions such as DOI or Handle, each with their own pros and cons. In the Netherlands, one open and free identifier that is used for digital academic object is location in the UI namespace of the National Bibliographic Number. The Konklijke Bibliotheek is the authority for the Dutch namespace. An organisation may request their own subnamespace at with the KB (the '99' following the 'ui' in the example below) after which the organisation may mint its own identifiers inside that namespace. Go to ??http://www.kb.nl/expertise/voor-bibliotheken/registration-agency-nbn to register your Persistent Identifier namespace.
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(...)
<didl:Descriptor>
<didl:Statement mimeType="application/xml">
<dii:Identifier>urn:nbn:nl:ui:99-123456890</dii:Identifier>
</didl:Statement>
</didl:Descriptor>
(...)
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This list may grow overtime based on community needs.
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(...)
<didl:Descriptor>
<didl:Statement mimeType="application/xml">
<rdf:type rdf:resource="info:eu-repo/semantics/DescriptiveMetadata"/>
</didl:Statement>
</didl:Descriptor>
(...)
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Every individual Item may have its own modification date. This date is included inside a dcterms:modified element. Its use is OPTIONAL.
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(...)
<didl:Descriptor>
<didl:Statement mimeType="application/xml">
<dcterms:modified>2010-12-14T14:22:48</dcterms:modified>
</didl:Statement>
</didl:Descriptor>
(...)
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URI | Description |
|---|---|
info:eu-repo/semantics/ClosedAccess | This type of access is the opposite of Open Access. Also referred to as "toll gated access". The main incentive her to gain access is by financial means. |
info:eu-repo/semantics/EmbargoedAccess | This type of access means the resource is Closed Access, until released for Open Access on a certain date. (this date can be specified elsewhere in the metadata) The incentives to embargo a resource has often to do with the fairness towards publisher to provide them an advantage as the exclusive first deliverers of knowledge. Also embargoes are used in sections of a Ph.D. thesis that are concerned with classified corporate information. |
info:eu-repo/semantics/RestrictedAccess | Open Access, but with restrictions. Often the Author wants to control the people who have access to for example a dataset. Access is provided in exchange for an e-mail address, to keep in touch with other people who are interested. |
info:eu-repo/semantics/OpenAccess | Open Access, this refers to access without restrictions, and without financial incentives. Access to the resource is gained directly, without any obstacles. |
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(...)
<didl:Descriptor>
<didl:Statement mimeType="application/xml">
<dcterms:AccessRights>info:eu-repo/semantics/OpenAccess </dcterms:AccessRights>
</didl:Statement>
</didl:Descriptor>
(...)
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The MimeType is specified inside the mimeType attirbute of the Resource Element. For an overview of available MimeTypes, please refer to the IANA registration of MIME Media Types.
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(...) <didl:Component> <!--MimeType contained in the MimeType attribute --> <didl:Resource mimeType="application/pdf" ref="http://myrepository.org/resource"/> </didl:Component> (...) |
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Please note that this concerns objects in the custody of the repository. |
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(...) <didl:Component> <!-- Object URI contained in the Ref attribute --> <didl:Resource mimeType="application/pdf" ref="http://myrepository.org/resource"/> </didl:Component> (...) |