A question for Steve, Hooves, and others

Good morning guys. I have a question, one that I hope is legit--since I am new to the room. And this is for anyone posting picks for a day's card.

I've noted that when listing your picks, each race usually has 4 horses listed. In your picks Steve, they are 1.2.A.B. (Can you explain the A-B for me?)

Most often, I bet only to win, with exactas in addition to my win bet. I've not ever bet multiple tickets, and have cashed multiple race tickets now and then when played. It's not to say that cannot change though.

So, when you are showing 4 horses listed for each race are any of you backing your 1st choice, or top horse, with a flat win bet?

Its easier to go 7 of 9 when one is choosing four horses per race, but in doing so, if not backing one or the other--cannot one STILL show a loss at the end of the day? (I know I can.)

I've been doing this for a good while, but I've never given myself the luxury of posting 4 possibles per race. On other boards though, I've rarely posted picks, so I need you guys to help me here.

Thanks to each of you in advance.