query: #title: en label required
  # Complex constraint from [[Property talk:P6597]]
  # Items with this property should have labels in English
  SELECT ?item ?value
  {
  	hint:Query hint:optimizer "None".  
  	?item wdt:P6597 ?value .
  	OPTIONAL { ?item rdfs:label ?l . FILTER(lang(?l)="en" )  }
  	FILTER ( !BOUND(?l) )
  }
  LIMIT 100