I use upvote so that I can see at a glance which comments I have read in a thread with alot of comments. It doesn''t matter whether I like the comment or not. I

I use upvote so that I can see at a glance which comments I have read in a thread with alot of comments. It doesn''t matter whether I like the comment or not. I use it like an email "read email" flag, but "read comment" in the case of HN