For complex legal reasons I don't understand, Microsoft had to submit to the French government a declaration of originality for Windows XP in order to pursue a software piracy case. It is my understanding that the legal department has already designated someone to take on this role for every release of Windows, but this case arose over a decade after Windows XP was released, so they had to dig back into their archives to find somebody who worked substantially on Windows XP and was still with the company. And that's how they found me. So my name is the one listed as the expert on Windows XP.
Although Windows XP is the collective effort of tens of thousands of people, it's not practical to put tens of thousands of names in a list of authors, much less get tens of thousands of notarized signatures. Instead three developers are nominated to represent the entire team. I don't know how they got chosen, but for legal purposes, those three developers are the authors of Windows XP.
Bonus chatter: One of my colleagues was interviewed by the school newspaper of the college from which he graduated. The topic was what it's like working on a large, complex piece of software. The story ended up headlined, "Bob Smith, Author of Windows 2000."