The code is available, and the protocol is no secret. It’s written in .NET though, which makes it not “proper” open source to some people, and I’m pretty sure all the maintainers are Microsoft employees, which makes it proprietary to many other people.[1]
Yep. Just a zip file with metadata, signing, and a bit of internal structure. Not unlike a wheel…
Not entirely unreasonably. “Open source” in that context is usually meant to imply “open governance”. ↩︎