PREFIX ocds: <http://data.tbfy.eu/ontology/ocds#>
PREFIX dct: <http://purl.org/dc/terms/>
PREFIX schema: <http://schema.org/>

SELECT ?hdoc ?qdocumenttype ?qdocumentlanguage ?qdocumenturl
WHERE {
	?id ocds:hasDocument ?hdoc .
	OPTIONAL { ?hdoc ocds:documentType ?qdocumenttype ;
						       dct:language ?qdocumentlanguage ;
						       schema:URL ?qdocumenturl } .
}