Sure, but were (relatively) limited compared to later releases. And the on-disk format was completely changed for windows 2000, hence me saying what you call "

Sure, but were (relatively) limited compared to later releases. And the on-disk format was completely changed for windows 2000, hence me saying what you call "NTFS" today is different to what it was originally. If you differentiate between ext2/3/4, which are all forwards-compatible like NTFS, you need to do the same here. Though that "forward compatibility" may be an update pass when first mounting an older version of the filesystem, which may break backward-compatibility. Though that may be desirable, especially if you want to use the new features. I remember there being a bit of a stink at the time when Windows2000 would automatically update the NTFS version and make it incompatible with NT4.0 if you didn't have the latest service pack, and even with that update some of the system tools didn't work on that filesystem anymore.