Why are there no A or B batteries?

#34 August 28:  Dave sent me this one.  Why are there no A or B batteries?  You have AA, AAA, C, and D.  Where are the A and B’s?  According to an article he sent me there are standards for A’s and B’s but the size and power are so slightly different from AA and C that they are impractical.  Originally A was the standard, but as electronics became smaller, AA and AAA became the preferred sizes. Now I want to know why 9-volt batteries don’t have a letter!!  According to Google, 9-volt batteries are called “E” but since they have the same voltage as C’s, the 9-volt name and snap stuck. 8/26