Query 28 - Extent_GAG: PREFIX strdf: PREFIX dataset: PREFIX gag: SELECT (strdf:extent(?o1) as ?ret) WHERE { GRAPH dataset:gag {?s1 gag:asWKT ?o1} } Query 29 - Union_GAG: PREFIX strdf: PREFIX dataset: PREFIX gag: SELECT (strdf:union(?o1) as ?ret) WHERE { GRAPH dataset:gag {?s1 gag:asWKT ?o1} }