<didl:DIDL
    DIDLDocumentId="urn:nbn:nl:ui:10-15290" <!-- Identification -->
    ...
>
    ...
</didl:DIDL>

urn:nbn:<country code>:<isil library code>-<object id>.

1. This DIDLDocumentId has in the first place a different Identifier than the OAI identifier for this record. The rationale behind this is that a DIDL document is an autonomous entity that can exist outside and separate of an OAI-record. However for easing the operational implementation, it is allowed to use the Identifier that is used for the OAI record when both, OAI record and DIDL document are inextricably bound together.
2. {ISIL library code} ISO/NP 15511: International Standard Identifier for Libraries and Related Organizations (ISIL)http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=52666
3. {object id} could be the database number. It is recommended to store this number in a separate field and not to auto generate from the database id because a database update in the future will change these numbers and the persistency could be lost.

<didl:DIDL ...>
  <didl:Item>
    <didl:Descriptor>...</didl:Descriptor> <!-- Identification -->
    <didl:Descriptor>...</didl:Descriptor> <!-- Modification date -->
    <didl:Item>...</didl:Item>
    <didl:Item>...</didl:Item>
    <didl:Item>...</didl:Item>
    ...
  </didl:Item>
</didl:DIDL>

<didl:Item> <!-- Level 1 Root Item -->
    <didl:Item> <!-- Level 2 Child Item -->
      <didl:Descriptor>...</didl:Descriptor> <!-- Identification -->
        <didl:Descriptor>...</didl:Descriptor> <!-- Modification date -->
        <didl:Descriptor>...</didl:Descriptor> <!-- Object type -->
      ...
      </didl:Item>
        <didl:Item>...</didl:Item>
        <didl:Item>...</didl:Item>
        <didl:Item>...</didl:Item>
    ...
  </didl:Item>
</didl:DIDL>

<didl:Item>
  <didl:Item>
    <didl:Descriptor>
      <didl:Statement mimeType="application/xml">
        <dii:Identifier>urn:nbn:nl:ui:10-6748398729821</dii:Identifier>
      </didl:Statement>
    </didl:Descriptor>
    ...
  </didl:Item>
  ...
</didl:Item>

1. For child Item elements of the root Item element accounts that this Identifier is NOT equal to the used OAI identifier or DIDL identifier
2. The Identifier in the root Item element CAN be the same as the DIDL or OAI Identifier, but this is not recommended
3. The namespace for dii has had to be declared in the DIDL tag
4. The Identifier in the HAS TO BE described as an URI when applicable

<didl:Item>
  <didl:Item>
  ...
    <didl:Descriptor>
      <didl:Statement mimeType="application/xml">
        <dcterms:modified>2006-12-20T10:29:12Z</dcterms:modified>
      </didl:Statement>
    </didl:Descriptor>
    ...
  </didl:Item>
  ...
</didl:Item>

1. Declare the dcterms namespace in the DIDL tag
2. The format of the date is Zulu-time; which means that it can be sorted as text
3. There can be only one Statement element in a Descriptor element, which means that dii:identifier and dcterms:modified reside in separate Descriptor elements

<didl:Item>
  <didl:Item>
  ...
    <didl:Descriptor>
      <didl:Statement mimeType="application/xml">
        <dip:ObjectType>info:eu-repo/semantics/descriptiveMetadata</dip:ObjectType>
      </didl:Statement>
    </didl:Descriptor>
    ...
  </didl:Item>
  ...
</didl:Item>

1. Declare the dip namespace in the DIDL tag
2. The ObjectType in the Descriptor Statement HAS TO BE described as an URI
3. The processing architecture we use for dissemination will be for General European repositories. The URI used is placed at the info namespace as info:eu-repo. (http://info-uri.info/) Meanwhile it is used as an un-official standard within the driver community.

<didl:DIDL ...>
  <didl:Item>
    <didl:Item>...</didl:Item> <!-- metadata -->
    <didl:Item>...</didl:Item> <!-- objects -->
    <didl:Item>...</didl:Item> <!-- jump-off-page -->
  </didl:Item>
</didl:DIDL>

<didl:Item>
  <didl:Item> <!-- one or many occurrences -->
    <didl:Descriptor>
      <didl:Statement mimeType="application/xml">
        <dip:ObjectType>info:eu-repo/semantics/descriptiveMetadata</dip:ObjectType>
      </didl:Statement>
    </didl:Descriptor>
  ...
</didl:Item>
<didl:Item> <!-- one or many occurrences -->
 <didl:Descriptor>
    <didl:Statement mimeType="application/xml">
      <dip:ObjectType>info:eu-repo/semantics/objectFile</dip:ObjectType>
    </didl:Statement>
  </didl:Descriptor>
  ...
</didl:Item>
<didl:Item> <!-- zero or one occurrences -->
  <didl:Descriptor>
    <didl:Statement mimeType="application/xml">
      <dip:ObjectType>
        info:eu-repo/semantics/humanStartPage</dip:ObjectType>
      </didl:Statement>
    </didl:Descriptor>
   ...
  </didl:Item>
</didl:Item>

• The info:eu-repo namespace is used with the following syntax: info:eu-repo/type/identifier For more information see
  http://info-uri.info/registry/OAIHandler?verb=GetRecord&metadataPrefix=reg&identifier=info:eu-repo/
• The semantics of the ObjectTypes mean for example that this Item states that the first sub-Item has or contains Descriptive Metadata.

1. (Mandatory when applicable) It is recommended to identify every separate component, for future reference or re-assemble purposous. This metadata set has its own identifier, which is NOT the same as the DIDL identifier.
2. If the date of the metadata has been changed, make sure the modification date of the root level Item is also being changed.
3. Declare the dc namespace in the start-tag of the Resource element where you use Dublin core.

<didl:Item> ... <!-- Below this line one can find links to one or more digital objects -->

  <didl:Item> <!-- First Item for a File/Bitstream -->
    <didl:Descriptor>
      <didl:Statement mimeType="application/xml">
        <dip:ObjectType>info:eu-repo/semantics/objectFile</dip:ObjectType>
      </didl:Statement>
    </didl:Descriptor>
    ...
    <didl:Component>
       <didl:Resource mimeType="application/pdf" ref="http://my.server.nl/report.pdf"/>
    </didl:Component>
  </didl:Item>

  <didl:Item> <!-- Second Item for a File/Bitstream -->
    <didl:Descriptor>
      <didl:Statement mimeType="application/xml">
        <dip:ObjectType>info:eu-repo/semantics/objectFile</dip:ObjectType>
      </didl:Statement>
    </didl:Descriptor>
    ...
    <didl:Component>
      <didl:Resource mimeType="application/pdf" ref="http://my.server.nl/appendix.pdf"/>
    <didl:Component>
  </didl:Item>

  <didl:Item> <!-- Third Item for a File/Bitstream -->
    <didl:Descriptor>
      <didl:Statement mimeType="application/xml">
        <dip:ObjectType>info:eu-repo/semantics/objectFile</dip:ObjectType>
      </didl:Statement>
    </didl:Descriptor>
    ...
    <didl:Component>
      <didl:Resource mimeType="application/pdf" ref="http://my.server.nl/datasheets.xls"/>
    <didl:Component>
  </didl:Item>

</didl:Item>

1. The order of the object components should be in a logical reading order! The Item with chapter 1 should be followed by the next sibling Item element that contains chapter 2, etc... This way the service provider can make a better presentation. Making the order explicit by placing sequence numbers is being specified in the next version of the specification.
2. If there are important modification dates for the Resource element, propagate these date changes upwards though out the parent Item elements that encapsulate the modified child Item element.
3. Only add Identifiers when there actually are any
4. If there are no Identifiers for the ObjectType Item elements, the Identifier of the DIDL element will be used by the service provider.
5. Use for a modified or Identifier element a separate <Descriptor> <Statement> element construction
6. The rule of thumb is that if a Bitstream or file has its own identifier, the wrapper is an Item element. To keep the possibility open for a Bitstream to have an Identifier, we use the Item element as default to wrap a resource location.

<didl:Item> ... <!-- Below this line; an Item with a link to one optional Intermediate page -->

  <didl:Item>
    <didl:Descriptor>
      <didl:Statement mimeType="application/xml">
        <dip:ObjectType> info:eu-repo/semantics/humanStartPage </dip:ObjectType>
      </didl:Statement>
    </didl:Descriptor>
    ...
    <didl:Component>
      <didl:Resource mimeType="application/html" ref="http://my.server.nl/mypub.html"/>
    </didl:Component>
  </didl:Item>

</didl:Item>