I was walking through the awards charts on www.nwa.com and noticed the off peak and rulebuster differences, but over on right hand side it had upgrades from both coach full fare, 12.5K, and select coach seats, 25K. I tried to find out what booking classes of service elligible for the 25K upgrade, but couldn't. Anyone have an idea which fares categories, i.e. V, K class, etc. elligible for the upgrade from coach to bus. class?