Hi, To my understanding, wine is a reimplementation of the MS system. As far as I understand, you take MS public headers and reimplement their functions. If that is how it works, then how do you deal with copyright? The MS headers certainly come with a copyright clause: how is it possible to redistribute these headers with wine? The reason why I ask this: I just rewrote an opensource implementation of a closed-source library. This opensource implementation is meant to be fully compatible with the closed source one: I reimplemented all the functions provided by their header, and anyone using the closed source one should be able to use my library as a replacement. My problem, though, is with the distribution of the header: Since I want to be fully compatible with the closed-source implementation, I have to, somehow, use the same header. I could probably modify it so that is *looks* different, but for the compiler, the API *needs* to be the same. Since you seem to have the same problem with wine (and you probably dealt with it succesfully), I wanted to ask you how you are solving this problem. Do you "rewrite" the headers? Do you copy them "raw"? Thank you, Christophe-Marie Duquesne