I believe that this refers to the issue of "side hop" that plagues some V70R & S60R, and was an attempt by Volvo (In the USA only????) to fix the issue.
The attempted "fix" was, I believe, to use less flexible bushing in some rear suspension components.
The real issue I have read was supposedly bad suspension design by Volvo in trying to get the 4C concept into a smaller than necessary location.
This upgrade received a mixed reaction, some cars it improved, some claimed it actually made theirs worse.
There are many places on the web where you can find more info on this subject.
A real time solution ( for me at least )to the side hop issue was put forward on a USA forum (
www.V70R.com) where by the total rear toe was set to 0 deg, and not the manufactures suspension setup.
This greatly reduced the issue of side hop on my 2004 V70R.
Cheers
Bob