Human blood groups are of 4 types with negative and positive of each types (Wikipedia). But according to this forum thread there are some other types too:
A+,A-,B+,B-,O+,O-,AB+,AB-,A1+,A1-,A2+,A2-,A1B+,A1B-,A2B+,A2B-
I'm going to make software for blood donation, where I need to put a dropdown list of actual blood types. I had intended to use:
[ Select Blood Group V ] [ O Negative ] [ O Positive ] [ A Negative ] [ A Positive ] [ B Negative ] [ B Positive ] [ AB Negative ] [ AB Positive ]
But now I am uncertain whether this is appropriate. What is the most suitable list of blood types for donors?