do you mean the Rh factor, which typically expresses itself as Rh+ or Rh
-? I forget exactly what the Rh
stands for, but it is something else found on the blood
. (Most cells in a human body have thousands of different signals and signs to identify them.) For instance I would say that I am A+, my husband is O+, and my ex flatmate AB-. That positive or negative sign is actually another genetic trait independent of the ABO and is the second way that blood is usually classified.