We may remember the experimental lcsh.info site that published the LoC vocabularies on line in SKOS. Well, while lcsh.info was closed down at some point, the official version is now up and running at http://id.loc.gov/authorities/.
This is great news. This means that all items in the LoC subject heading have now a stable, dereferancable URI; the URI refers to a (SKOS) Concept and is linked to broader and narrower terms. The implementation follows the LOD principles; the URI can be dereferenced in an HTML browser providing an RDFa annotated HTML page. To take an example, the subject heading for “Semantic Web” has the URI: http://id.loc.gov/authorities/sh2002000569#concept; dereferencing it leads to an XHTML+RDFa page. The RDF content can be accessed describing the concept in SKOS, providing a link to, eg, the concept of World Wide Web. This vocabulary gives a stable target to characterize the subject of various entities using, eg, the Dublin Core “subject” term. The site provides a search page and the whole dataset can also be downloaded in RDF/XML or n triples.
This is a huge service of the Library of Congress to the Semantic Web community. Thanks to Ed Summers and anybody else who took an active role in it!