What user details are shared with publishers through Apple News?

In iOS 9 Settings >> News >> News and Privacy, there's a long text that itemizes the privacy protections (and limitations) related to collection and use of individual and aggregated data.

Regarding "Disclosure to Third Parties", it says, in part:

We do not share any of your individual data with third parties...

I'm pretty sure that the publishers themselves don't have any access to your personal data. It's likely Apple News collecting info on what Apple News articles you read and like, so as to present news stories and articles that you might like to read in the "For You" section.