When I was a newbie, I was curious to know many things. I asked The Pharmacist what DT1 and DT2 meant. He sent me a link and explained briefly that DT1 are users trusted by theymos while DT2 are users trusted by the people theymos trusted.
After that brief explanation, I was curious why there is no DT3, DT4 and so on. But I didn't want to bother him the more.