"Each track in an OP must refer to exactly one infrastructure manager. There is a problem with OP {$this} ({?opLabel}) and its track {?track} ({?trackLabel}). This track has no values for this property"@en . "local" . "Infrastructure manager means any body or undertaking that is responsible in particular for establishing and maintaining railway infrastructure or a part thereof" . . . "\n PREFIX era: \n PREFIX rdfs: \n SELECT DISTINCT $this ?opLabel ?track ?trackLabel ?value\n\t \t\tWHERE {\n $this era:track ?track .\n \t\t\tOPTIONAL{?track rdfs:label ?trackLabel} .\n\t \t\t\tOPTIONAL{$this rdfs:label ?opLabel} .\n FILTER NOT EXISTS{?track era:imCode ?value} .\n \t \t\t}\n\t \t\t" . . "false"^^ . . . . "1.2.1.0.0.1" .