O receives O
A receives A,O
B receives B,O
AB receives A,B,AB,O
O donates A,B,AB,O
A donates A,AB
B donates B,AB
AB donates AB
and of course the RH factor is RH neg can give to RH pos but RH pos cant give to RH neg. It gets more complicated if you want to get into Phenotyping and all that.