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HomeDigital Library ProjectsStandards for Digital InformationLinked Open Data (LOD)Uniform Resource Identifiers (URI) for National Diet Library resources

Uniform Resource Identifiers (URI) for National Diet Library resources

Resources created by the National Diet Library (NDL) are identified by Uniform Resource Identifiers (URI), which can be used either to access the resource itself or to link it to other resources on the World Wide Web via HTTP protocol. To maintain stability and continuity, URIs comprise a fixed domain and path. Accessing a URI also provides users with additional information relevant to the resource.

Bibliographic data

NDL Bibliographic ID (NDLBibID)

ExplanationNDLBibID refers to identifiers given by the NDL to bibliographic data created by the NDL.
Modification or deletion of the associated resourceAlthough bibliographic data is subject to update, NDLBibIDs and their associated library materials do not change. If bibliographic data is deleted, however, its associated NDLBibID is no longer valid.
Domain/pathhttp://id.ndl.go.jp/bib/
Examples of URI containing the ID
  1. Kokuritsu kokkai toshokan geppo = National Diet Library monthly bulletin
    http://id.ndl.go.jp/bib/000000008550
  2. Guang yun jiao lu (Huang kan wen ji)
    http://id.ndl.go.jp/bib/a1000068044
  3. Kokuritsu kokkai toshokan geppo nenkan sakuin
    http://id.ndl.go.jp/bib/4108438
Number of IDs in useApprox. 28.8 million (as of March 2025)
ReferentBibliographic records of library materials cataloged in the NDL Search
Availability
  1. NDLBibIDs in the following format are included in metadata that can be retrieved from the NDL Search via API:
    <rdfs:seeAlso rdf:resource="http://id.ndl.go.jp/bib/xxxxxxxxx"/>
    The API supports OAI-PMH, SRU, OpenSearch, and other protocols.
  2. NDLBibIDs are included in the following open datasets:

IDs assigned to metadata of digital contents (NDL Metadata ID)

ExplanationThe term "NDL Metadata ID" refers to identifiers given by the NDL to metadata of digital contents in the NDL Digital Collections.
Modification or deletion of the associated resourceAlthough metadata is subject to update, NDL Metadata ID and their associated library materials do not change. The relevant bibliographic ID becomes invalid when the material indicated by the metadata is deleted or merged, etc.
Domain/pathhttp://id.ndl.go.jp/digimeta/
Examples of URI containing the IDKokuritsu kokkai toshokan nenpo = Annual report of the National Diet Library. 1953
http://id.ndl.go.jp/digimeta/3048007
Number of IDs in useApprox. 6.7 million (as of May 19, 2025)
ReferentBibliographic records of library materials cataloged in the NDL Search
AvailabilityNDL Metadata IDs in the following format are included in metadata that can be retrieved from the NDL Search via API:
<rdfs:seeAlso rdf:resource="http://id.ndl.go.jp/digimeta/xxxxxxx"/>
The API supports OAI-PMH, SRU, and other protocols.

National Bibliography Number (JPNO)

ExplanationJPNO refers to identifiers given by the NDL to bibliographic data of materials included in the Japanese National Bibliography.*
Modification or deletion of the associated resourceAlthough bibliographic data is subject to update, JPNOs and their associated library materials do not change. If bibliographic data is deleted, however, its associated JPNO is no longer valid.
Domain/pathhttp://id.ndl.go.jp/jpno/
Examples of URI containing the IDKokuritsu kokkai toshokan geppo = National Diet Library monthly bulletin
http://id.ndl.go.jp/jpno/00008614
Number of IDs in useApprox. 6.6 million (as of March 2025)
ReferentNDL Search results
Availability
  1. JPNOs in the following format are included in metadata that can be retrieved from the NDL Search via API:
    <rdfs:seeAlso rdf:resource="http://id.ndl.go.jp/jpno/xxxxxxxx"/>
    The API supports OAI-PMH, SRU, and other protocols.
  2. JPNOs are included in the open dataset Bibliographic ID List (tsv format)

* Includes all domestic publications submitted under the Legal Deposit System and those acquired through donation, purchase, or other means as well as foreign publications in the Japanese language. The NDL gives e-books and e-journals in the National Bibliography NDL Persistent IDs (info:ndljp) instead of JPNO IDs.

Authority data

URIs for authority data are allocated in different ways, depending on the type of authority. For further information, please refer to 2. URI Links under Description of Functions in the Web NDL Authorities.

NDL Authority Data ID: personal name/family name/corporate body name/work

ExplanationNDL gives Authority Data IDs to authority information for personal names, family names, corporate body names, and works. Every authority data is associated with two types of URI: an Authority Information URI embedding an Authority Data ID and a Name Entity URI.
Modification or deletion of the associated resourceAlthough authority information including names and titles are subject to update, Authority Data IDs do not change. If the authority information is deleted, however, its associated Authority Data ID is no longer valid.
Domain/path
  1. Authority Information URI: http://id.ndl.go.jp/auth/ndlna/
  2. Name Entity URI: http://id.ndl.go.jp/auth/entity/
Examples of URI containing the IDNatsume Soseki
  1. Authority Information URI: http://id.ndl.go.jp/auth/ndlna/00054222
  2. Name Entity URI: http://id.ndl.go.jp/auth/entity/00054222
Number of IDs in use1,268,695 (as of March 2025)
ReferentWeb NDL Authorities data
Availability
  1. Authority Information URIs in the following format are included in metadata provided via the Web NDL Authorities:
    • Authority Information URI: <skos:Concept rdf:about="http://id.ndl.go.jp/auth/ndlna/xxxxxxxx">
    • Name Entity URI: <foaf:Person rdf:about="http://id.ndl.go.jp/auth/entity/xxxxxxxx">
  2. Name Entity URIs in the following format are included in metadata that can be retrieved from the NDL Search via API (OAI-PMH, SRU, and other protocols are supported):
    • Personal name/family name/corporate body name: <foaf:Agent rdf:about="http://id.ndl.go.jp/auth/entity/xxxxxxxx">
    • Work: <dcndl:uniformTitle rdf:Description rdf:about="http://id.ndl.go.jp/auth/entity/xxxxxxxx">

NDL Authority Data ID: geographic name/uniform name

ExplanationNDL gives Authority Data IDs to authority information for geographic names and uniform names.
Modification or deletion of the associated resourceAlthough authority data including names and titles are subject to update, Authority Data IDs do not change. If the authority data is deleted, however, its associated Authority Data ID is no longer valid.
Domain/pathhttp://id.ndl.go.jp/auth/ndlna
Examples of URI containing the IDKanagawaken
http://id.ndl.go.jp/auth/ndlna/00258390
Number of IDs in use42,707 (as of March 2025)
ReferentDetailed information page of the Web NDL Authorities
Availability
  1. Authority Data IDs in the following format are included in metadata provided via the Web NDL Authorities: <skos:Concept rdf:about="http://id.ndl.go.jp/auth/ndlna/xxxxxxxx">
  2. Authority Data IDs in the following format are included in metadata that can be retrieved from the NDL Search via API (OAI-PMH, SRU, OpenSearch and other protocols are supported): <dcterms:subject rdf:Description rdf:about="http://id.ndl.go.jp/auth/ndlna/xxxxxxxx">

NDL Authority Data ID: NDLSH (topical term/subdivision) and NDLGFT (genre/form term)

ExplanationNDL gives Authority Data IDs to authority information for topical terms and genre/form terms. Every authority data for topical terms and genre/form terms is associated with two types of URI: an Authority Information URI embedding an Authority Data ID and an Authority Information URI embedding a label (literal of the topical term).
Modification or deletion of the associated resourceAlthough authority data including names and titles are subject to update, Authority Data IDs do not change. If the authority data is deleted, however, its associated Authority Data ID is no longer valid.
Domain/path
  1. Topical term: http://id.ndl.go.jp/auth/ndlsh/
  2. Genre/form term: http://id.ndl.go.jp/auth/ndlgft/
Examples of URI containing the ID
  1. Internet (topical term)
  2. Comics (genre/form term)
Number of IDs in use148,775 (as of March 2025)
ReferentDetailed information page of the Web NDL Authorities
Availability
  1. Authority Information URIs in the following format are included in metadata provided via the Web NDL Authorities:
    • Topical term
      • Authority Information URI embedding an Authority Data ID: <skos:Concept rdf:about="http://id.ndl.go.jp/auth/ndlsh/xxxxxxxx">
      • Authority Information URI embedding a label: <owl:sameAs rdf:resource="http://id.ndl.go.jp/auth/ndlsh/xxxxx"/>
    • Genre/form term
      • Authority Information URI embedding an Authority Data ID: <skos:Concept rdf:about="http://id.ndl.go.jp/auth/ndlgft/xxxxxxxx">
      • Authority Information URI embedding a label: <owl:sameAs rdf:resource="http://id.ndl.go.jp/auth/ndlgft/xxxxx"/>
  2. Authority Information URIs embedding an Authority Data ID in the following format are included in metadata that can be retrieved from the NDL Search via API (OAI-PMH, SRU, OpenSearch and other protocols are supported):
    • Topical term: <dcterms:subject rdf:Description rdf:about="http://id.ndl.go.jp/auth/ndlsh/xxxxxxxx">
    • Genre/form term: <dcterms:genre rdf:Description rdf:about="http://id.ndl.go.jp/auth/ndlgft/xxxxxxxx">

Digital content (digitized materials, online resources, etc.)

NDL Persistent ID (info:ndljp/pid)

ExplanationThe term "NDL Persistent ID" refers to identifiers given by the NDL to digital content in the NDL Digital Collections
Modification or deletion of the associated resourceAlthough the image and its metadata are subject to modification, the ID does not change.
Domain/pathDigital content in the NDL Digital Collections:
  • https://dl.ndl.go.jp/pid/
Examples of URI containing the IDDigital content in the NDL Digital Collections
  • Kokuritsu kokkai toshokan nenpo = Annual report of the National Diet Library. 1953
    https://dl.ndl.go.jp/pid/3048007
    * Previously, URIs like https://dl.ndl.go.jp/info:ndljp/pid/3048007 were used. Since December 2022, they have been changed to the above form. If you access the old URI, you will be redirected to the new one.
Number of IDs in useDigital content in the NDL Digital Collections
  • Approx. 6.7 million (as of May 19, 2025)
ReferentDigital content in the NDL Digital Collections
  • NDL Digital Collections content viewer
AvailabilityDigital content in the NDL Digital Collections
  • NDL Persistent IDs in the following format are included in metadata provided via the NDL Search and retrievable via API.
    <dcterms:identifier rdf:datatype="http://ndl.go.jp/dcndl/terms/NDLJP">info:ndljp/pid/xxxxxxxx</dcterms:identifier>
    <rdfs:seeAlso rdf:resource="https://dl.ndl.go.jp/info:ndljp/pid/xxxxxxxx"/>
    The API supports OAI-PMH, SRU, and other protocols.
    * The URI for the Digital Collections of the National Diet Library was changed to https://dl.ndl.go.jp/pid/ in December 2022, but NDL Search will provide the URI from before the change for the time being. If you access the old URI, you will be redirected to the new one.
  • Persistent IDs in the following format are included in the open dataset Bibliographic Data of the National Diet Library Digital Collections (xlsx and tsv format): <URL: https://dl.ndl.go.jp/info:ndljp/pid/xxxxxxx>
NoteOf the images of rare and old materials and books that have been digitized by the NDL and are stored in the NDL Digital Collections, those with expired copyrights are adapted to the International Image Interoperability Framework (IIIF), a method for sharing images online. The numbers included in the NDL Persistent ID are used as part of the IIIF manifest URI, as a means to identify the material.
e.g. Kokuritsu kokkai toshokan nenpo = Annual report of the National Diet Library . 1953
https://www.dl.ndl.go.jp/api/iiif/3048007/manifest.json

Reference: Digital Object Identifier (JaLC DOI)

JaLC DOI are managed by Japan Link CenterLeave the NDL website. . Please also refer to Assignment of a DOI name to an object by NDL.

ExplanationThe term "DOI" refers to identifiers given to digitized versions of NDL holdings included in the NDL Digital Collections and NDL publications. The ID consists of the NDL's prefix (10.11501) followed by a slash and the numeric portion of the NDL Persistent ID.
Modification or deletion of the associated resourceObjects are not to be deleted.
Domain/pathhttps://doi.org/
Examples of URI containing the IDKokuritsu kokkai toshokan nenpo = Annual report of the National Diet Library. 1953
Number of IDs in useApprox. 4.0 million (as of March 2025)
ReferentNDL Digital Collections content viewer
AvailabilityDOIs in the following format are included in metadata provided via the NDL Search and retrievable via API.
<dcterms:identifier rdf:datatype="http://ndl.go.jp/dcndl/terms/DOI">10.11501/xxxxxxx</dcterms:identifier>
<rdfs:seeAlso rdf:resource="http://dx.doi.org/10.11501/xxxxxxx"/>
The API supports OAI-PMH, SRU, and other protocols.

Contact for inquiries about URIs for NDL resources

Standardization Section, Digital Information Distribution Division,
Digital Information Department, National Diet Library

To contact us, please complete the Inquiry Form available on our website. Select 'Others', begin your message with 'Regarding Uniform Resource Identifiers (URI) for National Diet Library resources,' and then provide the details of your inquiry.

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