After NeXTSTEP 3.3 there was OPENSTEP 4.0.
OPENSTEP 4.2 is the last operating system release prior to Rhapsody.
Yes it’s confusing.
Considering how obsessed with UX that Jobs was, I don’t get how he thought the naming conventions were a good idea.
NeXT looks good in the logo, and they spent $100,000 on it.
FWIW, I like it but it is confusing and made harder by the fact they also didn’t stick to their own conventions much of the time.
AFAIK there isn’t any BSD code in Windows however the original TCP/IP stack in Windows was a port from BSD. But we are talking about the early 90s here and it’s long since been rewritten by Microsoft (or so they say, but I have no reason to disbelieve Microsoft)
Microsoft did leverage BSD code for common network utilities (ping, tracert, ftp, etc.), which still exist in Windows today, although Microsoft's preference is to leverage the "better" equivalent PowerShell cmdlets where available.
[0] https://en.wikipedia.org/wiki/Spider_Systems
[1] https://web.archive.org/web/20151229084950/http://www.kuro5h...
EDIT: If you want to hunt for BSD code, try taking a look at NT4[2].
[2] https://github.com/lianthony/NT4.0/tree/master/private/ntos/...
https://en.wikipedia.org/wiki/Windows_Vista_networking_techn...
Also OpenStep is an API rather than an OS. So macOS contains both NextStep and OpenStep code.