Yes. That is all those NS... prefix meant.

lproven · on Jan 11, 2020

I always thought that, too.

It's wrong.

Original NeXT classes were prefixed NX_. Then NeXT worked with Sun to make a portable version of the GUI that could run on top of other OSes -- primarily targeting Solaris, of course, but also Windows NT.

That was called OpenStep and it is the source of classes with the prefix NS_ -- standing for Next/Sun.

https://en.wikipedia.org/wiki/OpenStep#History

This is why Sun bought NeXT software vendor Lighthouse, whose CEO Jonathan Schwartz who later became Sun's CEO.

Unfortunately for NeXT (and ultimately for Sun), right after this, Sun changed course and backed Java instead.