Thanks for the link to the flat-package article (which I remember perusing when it was published), but I'm not certain of its applicability to this post.
When i let Software Update (on my lowly PowerBook G4 running 10.5.8) do a 'Download Only' of the iLife 9.0.4 item which appeared in the SU window, the only thing to arrive in my Downloads folder was "iLifeMediaBrowser_215.pkg" -- which itself is a flat package.
So, its
applicability came about as a result of my trying to guess what you meant by "
format". (it seems uncertainty breeds uncertainty
).
EDIT: thankfully, it looks like
dkmarsh has pieced the puzzle together nicely.
--
More info i dug up since last time: Although hosted by
google-code now,
xar had its roots in
OpenDarwin (may it
rest in peace).
