This came out of trying to uniquely identify elements on tantek.com, where there are multiple h-feeds in a page. I'm not sure how to uniquely refer to any of them. The suggestion is that an id property can be generated by taking the HTML id of the element that the h-* is on. It can be uniquely addressed by adding that as a fragment to the URL. For example, in the case of tantek.com, http://tantek.com#recent_articles should be his recent articles h-feed.