your preferred page version: <link rel="canonical" href="http://www.example.com/product.php?item=swedish-fish" /> inside the <head> section of all the duplicate content URLs: http://www.example.com/product.php?item=swedish-fish&category=gummy-candy . . .
. . .
understand that the duplicates all refer to the canonical URL: http://www.example.com/product.php?item=swedish-fish. The duplicate pages will be ignored and not indexed. Sphider-plus takes the rel="canonical" as a directive, not a hint. The canonical link may also be a relative path, but is not allowed to refer to a different domain. . . .
Sphider-plus