When it comes to matters of how things are worked at the airport please don't listen to the reservation agents. First of all, the vast majority do not have access to ACI (the system that generates the DM list and is used at the airports), in reservations only service directors have access to it. Most of the rez agents wouldn't know a DM list if it hit them in the face. Given that, they are very unaware of the gate agents job, I'm not putting them down, it's just something they don;t have training on because basically they have enough to learn about fare rules etc.