Thesauri 

The Digital Europa Thesaurus (DET) is a multilingual thesaurus covering the main subject matters of the European Commission's public communications.

Dating from 1978 when catalogues of the Central Library of the Commission of the European Communities (now the European Union) were computerised, ECLAS is a thesaurus created by the Central Library of the Commission of the European Communities for indexing the publications and documents acquired by the Central Library of the Commission. ECLAS was based on the Macrothesaurus of OECD and complemented by the ILO thesaurus. After creation of EUROVOC in 1984, convergence started in order to bring ECLAS in line with EUROVOC, but it was never complete. ECLAS contains nineteen areas of interest in a hierarchical tree structure consisting of four levels. ECLAS is fully available in English and in French.

The OP COMM ECLAS is maintained by the Publications Office of the European Union on the EU Vocabularies website. 

EuroVoc is a multilingual, multidisciplinary thesaurus covering the activities of the EU. It contains terms in 24 EU languages (Bulgarian, Croatian, Czech, Danish, Dutch, English, Estonian, Finnish, French, German, Greek, Hungarian, Irish, Italian, Latvian, Lithuanian, Maltese, Polish, Portuguese, Romanian, Slovak, Slovenian, Spanish and Swedish), plus in three languages of countries which are candidate for EU accession: Albanian, Macedonian and Serbian.  

EuroVoc is managed by the Publications Office of the European Union, which moved forward to ontology-based thesaurus management and semantic web technologies conformant to W3C recommendations as well as latest trends in thesaurus standards. The thesaurus is disseminated on the EU Vocabularies website. 

EuroVoc users include the European Union institutions, the Publications Office of the EU, national and regional parliaments in Europe, plus national governments and private users around the world.