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

SELECT ?itm ?qdescription ?qclassificationscheme ?qclassification ?qadditclassificationscheme ?qadditclassification
WHERE {
  ?id ocds:hasContractedItem ?itm .
	OPTIONAL { ?itm dct:description ?qdescription } .
	OPTIONAL { ?itm ocds:classificationScheme ?qclassificationscheme .
	           ?itm ocds:hasClassificaton ?qclassification .
  OPTIONAL { ?itm ocds:additionalItemClassificationScheme ?qadditclassificationscheme .
	           ?itm ocds:hasAdditionalItemClassificaton ?qadditclassification }} .
}