What do the letters on the back of the ignition switch say?

[iCapture]

I am trying to figure out which prongs on the back of my 1975 280z ignition switch control what. I see that there are some letters on the back of it and they are

B S

A IG

R

I have been looking thru my Chiltons and I am not seeing anything.

This is what i am looking at:

Can someone help??

Is there a female plug that goes into the back of it? I looked around and I dont see a plug that corresponds with the pattern. If there is a plug, could I get a picture of it by chance?

Adam

[Arne]

Battery

Accessory

Start

IGnition

Radio (I think)

Yes, there should be a single plug with five matching wires. Sorry, I don't have a picture.

[geezer]

R-Run

[sblake01]

Not a picture of the plug but this comes in handy if you want to check the functionality of the ignition switch itself at the particular key positions: