'51 Tudor Ign Switch Help

[Shoebox]

Installing new wiring in my '51 dash while it is out of car, and I'd REALLY appreciate advice on corresponding the terminal markings on my ignition switch with the labels of same on diagram that came with harness, I have attached pics of both. My switch has 3 terminals marked Battery, Acc, and Ignition, and an unmarked center terminal. The diagram shows Coil, Am, ST, and Acc, which I get. I imagine Coil might be my Ignition, so the other 2 are which? I just don't want to guess and smoke something, so any assist most appreciated. Thanks!