Basic usage

The home page lists all of the concepts in the thesaurus. Use the text box to filter the list of concepts. Click on a concept (e.g., Libraries) to go to a page describing the concept. Each concept page contains links to other broader, narrower or related concepts, as well as additional scope, editorial or historical notes about the given concept.

Menu bar

The About link leads to a page that provides some information about t4gm.info.

The Validation link calls the W3C's Markup Validation Service to confirm that the current page is standards-compliant.

The Distillation link calls the W3C's RDFa Distiller to generate an RDF/XML file from the current page.

The Help link leads to the page you are currently viewing.

Site search

Because t4gm.info encodes its metadata in XHTML+RDFa, it is directly indexable by Web search engines. As a consequence, free text search over the thesaurus content can be done by simply restricting a given engine's results to those found in the www.t4gm.info domain. For example, all pages containing the term "fish" can be found by typing the query 

        site:www.t4gm.info fish

into the Google search box.

Linked data support

The home page and concept pages use the SKOS vocabulary to encode the thesaurus metadata in RDFa. These pages leverage the RDFa Distiller service to support content negotiation by Semantic Web user agents accepting RDF/XML or Turtle instead of XHTML+RDFa.

The following table summarizes the mapping from tags used in TGM (version dated 2:28PM 10/1/2008, downloaded from http://www.loc.gov/rr/print/tgm1/tgm1.txt) to the SKOS vocabulary (as described in "SKOS Simple Knowledge Organization System Reference Editors' Draft 1 October 2008 $Revision: 1.73 $.")

Mapping of TGM to SKOS in t4gm.info
Tag in Downloadable TGM file SKOS predicate
No tag (1st line in record) skos:prefLabel
UF skos:altLabel
USE skos:related
BT skos:broader
NT skos:narrower
RT skos:related
SN skos:scopeNote
HN skos:historicalNote
CN skos:editorialNote
FUN skos:changeNote
Facet ignored
TTCForm ignored
TTCRef ignored
TTCSubd ignored
TTCSubj ignored
FCNgmgpc ignored
FCNlctgm ignored
TNR ignored

Suggestions for improving this mapping are welcome.

API

t4gm.info also provides a simple API for requesting pages listing a filtered set of concepts. 

        http://www.t4gm.info/matches?q={string}

will return an XHTML+RDFa page listing concepts where string is a prefix of a token in the skos:prefLabel, or is a prefix (including whitespace) of the full skos:prefLabel. For example, a GET request issued against 

        http://www.t4gm.info/matches?q=beach

will return a page listing matches for "beach". The call ignores case and non-alphanumeric characters. This method is used through an AJAX call on the home page to filter the list of concepts.

Match pages support content negotiation in the same manner as the home page and concept pages.