The first time "derivative works" appears is in 4.(a) and it is not defined; it appears again in 4(b) chained to Work ("the Work and derivative works thereof"), but these terms are also not defined.
Then, in section 7, we get what looks like a definition of Derivative work, but I'm not sure that it extends to the earlier sections.
It also wasn't clear to me whether compiled object code of unmodified source counts as a derivative work or not. Section 4 implies that it might be, but the definition in section 7 stipulates that you have modify the source to create a derivative work. So, I'm not clear on what this license says about non-source distribution.
Eric Friedman
