Unfortunately, there is some Microsoft code available on the Internet. More unfortunately, Google has indexed some of it. I was searching for an undocumented function and ran across something that seemed to describe it. I clicked on the link, and fortunately the indexed page was just a reference to the actual source file, because the source file was Microsoft's. (The source file was also available. No, I didn't look at it.)
Be very careful: reading Microsoft's source code is a clear way to taint yourself as a developer. --Juan