- Existing controlled vocabularies (CVs) from DDI are available in RDF format, represented using SKOS, with each CV as a skos:ConceptScheme and entries as skos:Concepts. Versioning is supported. - Mappings are defined between DDI and other vocabularies like PROV-O, Data Cube and DCAT to represent relationships between statistical data, studies, datasets and catalogs. - Work is ongoing to map DDI-XML to the Disco ontology to represent statistical metadata in RDF, with the aim of enabling the publication and linking of statistical data as Linked Data on the web.