NGDV stamp mark?

I'm used to seeing marks over stamps, but I've never seen this one. Can't quite make out what it says though. Anyone know? Also what is the official term for a stamp that's been used that has a mark on it, isn't there a word for the mark or no?

I'm used to seeing marks over stamps, but I've never seen this one. Can't quite make out what it says though. Anyone know? Also what is the official term for a stamp that's been used that has a mark on it, isn't there a word for the mark or no?