Recently while scrolling around the internet I've found a few websites that have w2 at the beginning of the URL instead of www. I'm not really sure of what the purpose of using this form of canonicalization may serve, other than just to be different. But after seeing that the Vatican's website also has it now, I'm starting to think it may actually have a functional purpose.
The Vatican's website has a lot of interesting redirects, but for me at least they all end up going back to w2.vatican.va as the base URL.
www.vatican.va redirects back there, google redirects there although it was indexed with the www.
So what is the purpose of using w2 instead of www?