The National Diet Library (NDL) made the "Web NDLSH," the web version of the National Diet Library Subject Headings (NDLSH), available on June 30, 2010 (Japanese only).

The NDLSH is a thesaurus (controlled vocabulary list) maintained by the NDL as a subject access tool, and is also used for search by "subject heading" in the NDL-OPAC. The NDL had formerly been providing the NDLSH in book form; since 2005, in PDF and text format on the NDL website. Now the Web NDLSH is released using the SKOS (Simple Knowledge Organization System), aiming to be applied to various applications or systems on the web.

The SKOS data model adopted in the Web NDLSH is suitable for expressing controlled vocabularies like subject headings or classifications on the semantic web, and has already been used for providing subject headings in other countries, as in the Library of Congress Subject Headings (LCSH).

The Web NDLSH allows the following services:
1) Reference function to the URIs of subject headings by assigning a URI to each of them
2) Download of each datum in three formats: RDF/XML, RDF/Turtle, JSON; download of the entire data in two formats: RDF/XML, TSV
3) Mechanical coordination with external systems that enables searching from external applications by using the SPARQL, an RDF query language
4) Creation and display of links to the LCSH and the Wikipedia when they have subject headings or terms corresponding to each subject heading of the NDLSH
5) Search by the National Diet Library Classification (NDLC) and the Nippon Decimal Classification (NDC) as well as by headings or reference
6) Provision of main-heading/subdivision combinations such as "United States -- Foreign relations -- Japan -- History -- 19th century" in addition to main headings of topical names
7) Graphical display of the NDLSH thesaurus structure

We also intend to provide resources other than the NDLSH, such as name authority or the NDLC, to make them more user-friendly on the web.

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