While not practical for most members, it is even possible to use up to 4 years of points for a single reservation that would cross two Use Years.
With a 150 point contract and a June Use Year, a member could bank their 2009 points and then use their 2010, borrow 2011 and even borrow 2012 points for a single reservation for a stay from May, 2011 into June, 2011.
The banked 2009, current 2010 points and points borrowed from 2011 could be used for the dates in May, 2010 and points borrowed from 2012 (along with points from the 2011 use Year) could be used for the dates in June, 2011.
For that example, a member could have access to 600 points for a single reservation.