The headers themselves are under copyright, of course, but the definitions inside them can be copied/reused for interoperability reasons (something that is espe

The headers themselves are under copyright, of course, but the definitions inside them can be copied/reused for interoperability reasons (something that is especially protected in EU but i think also in US). So while you cannot distribute the header files, you can write your own parser that generates new header files (for C or any other language) that are compatible with the Microsoft header files as long as they aren't the same. Of course IANAL but AFAIK this is what several projects (especially compilers and interpreters) that need to hook with other APIs are already doing.