@prefix skos:	<http://www.w3.org/2004/02/skos/core#> .
@prefix isac:	<http://webisa.webdatacommons.org/concept/> .
isac:_roofing_	skos:broader	isac:structural_surface_ .
isac:_wall_	skos:broader	isac:structural_surface_ .
isac:_ceiling_	skos:broader	isac:structural_surface_ .
isac:_bedding_	skos:broader	isac:structural_surface_ .