This was going to be a comment on Danny Ayers' Feed splicing and attribution post, which is about indicating Atom feed sources. I was going to just say that I thought Danny's suggestion was a good one, but I am working on something similar right now for the iCite net and thought it would be useful to mention it—and thought that mention would better go here.

(You might want to read Danny's post to get the context for this.)

With the iCite net, I am trying to account for cases where you end up with a feed of a feed of a feed ... (and, more generally, of a copy of a copy of a copy . . . of some content).

So I am thinking about the feed or content "source" in terms of both the first point of publication on the network and the immediate source of the current copy / derivative versions of the feed or content. Something like:

http://mycontent feeds off of http://hercontent, and
the network origin of this content is http://othercontent

The idea is that if you have the origin point and your current point, you can trace through all intermediaries when you need to, starting from either end.

Also, in the iCite net, these links work like two-way links in that the origin gets links to all copies / derivative versions, as all sources in general also link to those that "feed" off of them.