You may also want to search for threads on extended norms, there have been a lot in the past. Extended norms are done on the SB-V too. As to your question of why you would need that information? I am not sure. I suppose it can tell you that they are even higher in an area, but when the area is already at 18/19 that is somewhat assumed...isn't it? those are just my thoughts, not official by any means. I am sure there are some other benefits. I guess for us it was useful to let schools know just how far above the norm he was. More useful for the schools probably than for us. We had already figured that. But I am sure some schools wouldn't even look at/accept/understand extended norms.