Well, we are not the developers of the dpmaster program, nor maintainers of deathmask.net.
Dpmaster works not only with OpenArena, but also with some other games (on deathmask, you can find other games like Tremuluos and Urban Terror).
I don't know a lot about it, but
from what I understood, the dpmaster software author may be
Mathieu Olivier, while a certain "Willis" should be deathmask dpmaster maintainer. "
rm", instead, is a guy who
modified dpmaster software to create his own dpmaster server,
supporting IPv6 with current OpenArena versions (standard dpmaster does not show 0.8.x IPv6 OpenArena servers), however servers and clients do not use that unofficial master server unless manually instructed to do so.