@aaronpk A starred article is a private favorite — generally it means something you want to come back to later for some reason. It’s common to have a special pseudo-feed that shows just starred articles, so a user can find them all easily.
I haven’t worked with current syncing system APIs much yet: my experience is mainly with NewsGator and Google Reader APIs, both now defunct. I vastly preferred NewsGator’s API, because it was designed as a syncing system, where Google Reader’s API was designed for Google, and was never publicly documented or supported, and didn’t work very well for apps like Evergreen (there were lots of ambiguous cases).