At this point, BUILDING.txt contains a number of mis-statements. It is structured in a way which makes the Derby build look complicated and intimidating. The build instructions need to be thoroughly overhauled and divided into two main sections:
1) The simple build instructions for people who are new to the community. This will be a build with few pre-requisites which just works out of the box.
2) Trickier build instructions for people who want compile-time checks for the different platforms which Derby supports.
While we're at it, I suggest that the revised instructions live in an html file rather than a flat text file. I think this will result in a document that is more readable and easier to navigate.