AGROVOC is a multilingual structured thesaurus for the agricultural domain, which is owned and maintained by an international community of Agricultural Research Information Institutions. AGROVOC is used all over the world by researchers, librarians, information managers and others, for indexing, retrieving, and organizing data in Agricultural Information Systems. It currently includes 579523 terms in 19 different languages.
Since 2004 (1) the AGROVOC (within the Agricultural Ontology Service) Initiative underwent a process of semantic cleaning and enrichment to make it a base vocabulary for semantic web applications.
To maintain collectively such a semantically rich concept scheme, a tool called "AGROVOC concept server workbench" was developed. In early June 2010 the "AGROVOC concept server workbench" went into production (http://126.96.36.199:55234/agrovocdevv10/)
In 2004 there was clear intention to adhere to Semantic Web standards for Knowledge Representation and interchange, though there were no suitable model nor standard available for expressing a concept scheme without losing the richness of meaning contained in the original thesaurus. Namely, the first versions of SKOS (which, also, was still not recommended by W3C) were insufficient to express relations between terms.
For this reason the AGROVOC team at FAO developed a model that was based on 3 layers: concept to concept relations, term to term relations and string to string relations. This conceptualization was formalized in an OWL model.