The CDSEO url is listed in the canonical tag. A page can be accessed by several different urls, for example:
http://www.example.com/page.html
http://www.example.com/page.html?sort=X
http://www.example.com/page.html?somevar=X
http://www.example.com/page.html?blahblahblah
The possibilities are endless. CDSEO puts the canonical tag of
http://www.example.com/page.html on the page, so whenever any one of the infinite other possibilities are accessed by search engines, they consolidate all of the page rank to the one url.