[ksaj]

You can see this with Linux as well. For example, with ext# file systems, extended attributes allow you to make files append-only, copy-on-write, or give files project and version numbers. It also lets you decide which files are or are not compressed if the file system is set to be compressed. Other attributes determine what happens to a file when you delete it (nothing, zeroing the sectors, etc)

The chattr/lsattr commands are used for accessing them.

The only time I've seen these come up are for secure locations that set log files to append-only. But I'm sure there are people out there that swear by extended attributes.