[ggm]

No disagree, Both came later IIRC. Melbourne unis work on appletalk and Apple file system support was in the late 80s and I believe POSIX xattr spec work was mid nineties, NTFS was '93 or so. The fork model in apple file store was eighties work.

[nullindividual]

GP wasn’t arguing about timelines.

NTFS ADS were created to accommodate Mac OS resource forks on network volumes when using AFP.

[ggm]

Gotcha! I assumed they were invented for Windows centric reasons.

[adrian_b]

The concept of extended file attributes has been introduced by HPFS, in OS/2, in 1989.

From HPFS it was taken by SGI XFS (the ancestor of Linux XFS) and MS NTFS, both in 1993.

From there it has spread to various other file systems and specifications.

The concept of resource forks is earlier, but both are examples of using alternate data streams in a file.