Two-three years ago, I experimented (in Windows) with NTFS ADS meta-data (Alternate Data Streams). It seemed like an interesting idea, but it is certainly not "portable".
Is there an NTFS-ADS aware tool which can read and/or write this ADS data?
Also, do any of the `nix commonly used/preferred file-syystems support similar secondary streams"?
The ntfs-3g FUSE driver (almost certainly the one you're using if you've got read/write) talks ADS, but not by default (except on Linux apparently, where ADS are mapped to extended attributes by default).
From ntfs-3g's man page:
Alternate Data Streams (ADS)
NTFS stores all data in streams. Every file has exactly one unnamed data stream and can have many named data streams. The size of a file is the size of its unnamed data stream. By default, ntfs-3g will only read the unnamed data stream.
By using the options "streams_interface=windows", you will be able to read any named data streams, simply by specifying the stream's name after a colon. For example:
cat some.mp3:artist
Named data streams act like normal files, so you can read from them, write to them and even delete them (using rm). You can list all the named data streams a file has by getting the "ntfs.streams.list" extended attribute.
As for the flip-side of your question, the basic umbrella term for this extra metadata would be extended file attributes. The various unices and their filesystems have support for this kind of thing under various names: the ext* family and many other Linux fs's call these xattrs.
