Building a KERNEL, building a RELEASE ir BUILDING WORLD relies on several environment variables, some of high importance. Looking into build, release, config I realised, that variable "KERNCONFDIR" is neither explained or documented in either of the above man pages (I would expect to find any documentation in build(7).
KERNCONFDIR shouldn't be changed in normal use, hence the lack of documentation on it. Those expecting to experiment should be working from the source code.