There is a distinction between what both of you are saying. The crux of the issue is that once the patent expires in 2015, we only have 6 years of infringement to recover. So after the parent expires we can only go back to 2009 to recover $s if we notified the infringer in 2009 or prior. The important point here is if we notified someone in 2006 and the patent expired in 2015 and we are in 2015, then we forfeit 2006 to 2008 for infringment. In 2016 we would forfeit 2009, in 2017 = forfeiture of 2010, until reach 2021. In 2020, you could only recover infringment damages for any products sold in 2015, which could equal much less than what were the original infringing products. Corrections welcome ...