Media resources in an entry with APP

I've seen more than a few Pace docs regarding how to handle media 
referreed to by an Atom entry being published, and am having difficulty 
making a decision. How are people currently updating their entry after 
uploading the related media? Are the img references in the Atom entry 
being set to "id:ajfei4242" from the id in the media post? Are they 
changed to the Location url given from the media post? etc.

The APP spec clearly states how to upload media, but not how to 
indicate that an Atom entry is using it. If there's a Pace on track for 
integration into the APP spec, which one is it?

Thanks,
Ben