PREFIX rdfs:<http://www.w3.org/2000/01/rdf-schema#>
PREFIX : <http://admin/delivery.owl#>

SELECT ?individual ?colour
WHERE
{
	{
		?individual a :Person.
		:Person rdfs:comment ?colour.
	}
	UNION
	{
		?individual a :Person.
		BIND("red" AS ?colour)
	}
}