See minutes online for a more detailed record of the discussions.
We agreed that we would create a WP that may require a browser extension of the author/publisher to inject a script in a similar way to the scripts injected for MathJax. This builds on the concepts introduced in BFF. We are leaving PWP aside for now. EPUB 4 will be a packaged WP, possibly with stricter rules. We have not determined much about relationship to EPUB 3 except that, as it says in the charter, there will be functional round-tripping.
(this is https://github.com/w3c/wpub/issues/207) This is an issue of author stating preferences. There was discussion about whether this could be accomplished using CSS. Since styling across multiple DOMs cannot be done with CSS, the group agreed to put hints in the infoset.