So all the actual filesystem entries are basically soft or hardlinks to the most recently selected version? Time Machine on OS X works that way (as do a few ot

So all the actual filesystem entries are basically soft or hardlinks to the most recently selected version? Time Machine on OS X works that way (as do a few other incremental backup solutions, I believe). Notably in Time Machine's case, it hacks a way to hardlink to entire directories which haven't changed, which is normally not possible. (There's a parallel here with how immutable data structures are managed.)