I have asked a question which has yielded a massive list-type answer.
There are several points within this answer that I would like more information about, but placing them all into a comment (which might not even fit) would be really messy / illegible and if someone did this to my answer I probably wouldn't even respond.
Could there be a feature where I as the OP can highlight parts of the answer which will notify the answerer, giving them the option to provide more information about what I've highlighted? The highlights could be yellow but only visible to the answerer (so that while browsing the website there isn't yellow everywhere).
This would be particularly useful for this style of answer, especially because I'd like information on 5 or more of those points.