> > What other metadata needs to be preserved on a per-file basis?
>
> I'll second the x mode bits. Dunno what you are doing about tags, but
> maybe those, and, of course, delta comments.
Definitely, but delta comments are per-revision, not per file. They may make reference to individual file changes in the text (perhaps in a programmatically extractable way), but files don't get changed; configurations do.