Regardless of whether we chose to use an id or the role attribute to mark the toc, authors can put several instances of it in their index.html, so we need to agree on what that means.
Only the first one matters, everything else is ignored
Only the last one matters, everything else is ignored
"The Toc (tm)" is the union of however many toc elements there are.
Regardless of whether we chose to use an id or the role attribute to mark the toc, authors can put several instances of it in their index.html, so we need to agree on what that means.
I'd go with 1.