Ask HN: What do triple-asterisk HN replies indicate?

A few times now I've gotten the following email from hnreplies.com: > [SOME_PERSON] replied to your comment [link]: > > * * * Then when I go to view the subsequent comment, it is filled in. Is there an HN client which posts this initial message? Or is are the individuals doing it manually? Is there a subculture phenomenon occurring? Cheers, Md