Library of Congress Linked Data Service

The LC Linked Data Service is an initiative of the Library of Congress that publishes authority data as linked data.
It is commonly referred to by its URI: id.loc.gov.
The first offering of the LC Linked Data Service was the Library of Congress Subject Headings dataset, which was released in April 2009.

Datasets

Library of Congress Subject Headings
Library of Congress Name Authority File
Library of Congress Classification—because LC Classification uses a different MARC format than LC Authorities, mapping LC Classification to MADS/RDF was more difficult than mapping LCSH or LCNAF.
Library of Congress Thesaurus for Graphic Materials
Various MARC codes
Various preservation vocabularies

The Library of Congress offers users the opportunity to create their own datasets with library application profiles.

Formats

The service presents data in MADS/RDF and SKOS where appropriate, but also uses its own ontology to describe classification resources and relationships more accurately. All records are available individually via content negotiation as XHTML/RDFa, RDF/XML, N-Triples, and JSON.
Each vocabulary is also available to download in its entirety. Id.loc.gov does not currently provide a SPARQL endpoint.

Uses

All of LCSH are crosslinked with , an authority file from the Bibliothèque nationale de France.

Technical aspects

The id.loc.gov site initially used a fairly lightweight Python program to serve linked data.
See also