instance
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadMap-G
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadMap-S
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadMap-P
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadMap-O
http://www.openlinksw.com/schemas/virtrdf#DefaultServiceMap-G
http://www.openlinksw.com/schemas/virtrdf#DefaultServiceMap-S
http://www.openlinksw.com/schemas/virtrdf#DefaultServiceMap-P
http://www.openlinksw.com/schemas/virtrdf#DefaultServiceMap-O