It seems that some Toronto taggers are no longer content to scrawl their own names on blank concrete canvases around the city and are trying instead to make more of a cultural statement. Last year, references to composer Gustav Mahler popped up in several places around town. This year, a more cryptic stencil has appeared on the Humber Bay Arch Bridge, boldly proclaiming "ISBN 486-28495-6" for all to see and ponder. This International Standard......