You need the raw scores to be able to calculate them, and as far as I know they only apply to WISC-IV. There is a techical report that you can find online. http://www.pearsonassessments.com/N...C-8E4A114F7E1F/0/WISCIV_TechReport_7.pdf

The test doesn't do a good job at discerning the highest levels, and this is an attempt to counter that. I think the extended norms give extra information; but that they have to be taken with a grain or two of salt.