I'm not a lawyer either and I wonder about the scope of Apache patent grant. Does it give you the right to use any patents the software in question "uses" in any possible context? Or does it simply allow you to modify the software any way you like and not get sued for infringement? But then how much can I modify it and still retain the right to use those patents? I mean if I create a totally unrelated software package which however shares some code with the original work, can I keep on using those patents anyway I want?