What does the "I" stand for in blood crosses?

Question

What does the "I" stand for in blood crosses?

Answer 1

It doesn't really stand for anything. The "I" is simply an easy way to denote the different alleles of blood types when you're making crosses, like I^AI^B x I^BI^B. Plus, it allows for people to not so easily confuse the letters with other commonly used ones like "X, Y", which can hold different meanings entirely (X = female, Y = male).