This goes along with my last question involving nel cor piu non mi sento by paganini, however this is a picture of what I was literally looking at. Thanks to you guys, I learned what small letter "A"s meant. Would anyone happen to know what the big letter "A"s above the staff mean, and if it is similar in meaning to the small "A"s in the other post I had? Thanks everyone.
I grabbed copies of a couple different editions from online warehouses, and none of them had a big "A" in the 4th variation. As Caters wrote, it is most likely a rehearsal mark (tho' pretty silly to have one in such a short variation). Compare with "A" placed below the notes in the 3rd variation, which you noted you already understand.