Windows kernel-mode development documentation has always been as inadequate as it is voluminous. Back in 1992-93, Microsoft initially intended to ramp up a consultancy practice to support a strategy of keeping a monopoly on driver development. That idea was quickly dropped, but its effects lingered on. For many years, there was the published documentation, which, in its thousands of pages, did not quite tell you what you needed to know -- and then there was the good stuff, which was only available under NDA for big money. It may still be so.