Myself and Nikunj Mehta have been working on an Internet Draft for a small extension to Atom and AtomPub to enable modelling master-detail relationships (e.g. purchase orders and line items) in feeds and collections. We have frequently found a need to express this kind of relationship when attempting to define Atom/AtomPub interfaces for enterprise applications, so we feel it would be useful to try and define a standard mechanism for this. We’ve missed the current window for submitting Internet Drafts, so for now the draft resides here. Please join the discussion here.
Finally a word of thanks to Bill de hÓra and Ashish Motivala for taking the time to review early drafts and provide valuable feedback and improvements.