Ask HN: A post can be [flagged] and [dead] but how?

A post I was looking at got [flagged] apparently at some point while I was reading the article, and then was marked [dead] (he's dead Jim!) by the time I came back to comment on it.

Totally understand that the site needs moderation and all, but when I came to this page (the submission page) I didn't see any link to rules or guidelines. Though now that I look, they are linked on the homepage.

Still wondering what those tags mean and how they are applied. Is there any transparency in HN moderation?