At the moment, I can mark an e-book edition as 'owned'; but (unfortunately for me, lol) there's several places I could own it, all mutually exclusive.

At least one dimension of this is at least partially encoded in the 'editions' interface (is it physically on my shelves in my house, or is it in my eReader?); but there's an orthogonal dimension in both cases - for me, that's "owned on iBooks" (for my most ancient books), "owned on Amazon" (for the majority of my books), or "owned on Kobo Store" (nowadays.)

I imagine the same feature (sub-lists for the 'owned' feature) could be mapped to physical books as well - where is my book, in my basement storage, up on the shelf in my home, at my parent's place ... and so on.

(This isn't at all high priority for me, but I thought it was worth pointing out as an enrichment of the data-model that would have at least some value for me, personally.)