For blood type B, the genotype is BB or BO with A as the antigens and B as antibodies. The blood type AB has the genotype to be AB. The antigens are both A & B, and no antibodies on the blood plasma. The blood type O has the genotype to be OO. There are no antigens but has antibodies to be A or B. Rhesus factor or the 'D' antigen is also found on the surface of the red blood cell. Those with it are seen to be rhesus positive or Rh+ and those without are rhesus negative or Rh-.
Dark of the Moon. The Dark of the Moon is traditionally the last three days of the Lunar cycle, immediately preceding the New Moon, and the time when the night sky is notably absent the presence of the Moon.
This earlier definition says a Blue Moon is when there are 4 Full Moons in a season rather than the usual 3. The Blue moon is the 3rd full moon out of the 4. This definition gets a bit complicated and it's origins are murky. One school of thought has to do with the naming of the full moons.