Need to examine how Sub-sections, (H3 and H4 and H5) might work,
Should they be distinct from posts? (I.e. an inserted block, that isn't obviously "belonging/connected" to a specific user's post)
They'll be needed for
Trello card: b1yETj6R
Flow allows any reasonable HTML markup, including markup header <h2>, <h3>, <h4> (wiki headers == === ==== just pseudo-marking wrapper for them). However, as shown by tests, in Flow they just bold text larger. Sections and subsections are defined mechanisms of Flow. No new branches.
example:
In the Flow == can not be seen:
https://ru.wikipedia.org/w/api.php?action=parse&text={{Википедия:Песочница/Flow}}__TOC__&prop=sections&contentmodel=wikitext&format=xml
On a regular forum == seen:
https://ru.wikipedia.org/w/api.php?action=parse&text={{Википедия:Форум/Общий}}__TOC__&prop=sections&contentmodel=wikitext&format=xml
( from Flow feedback ru.wiki )