NEED HELP FAST! What is this on the wiring schematic? Wiring the car now

What is this on the wiring schematic? The circled item. And what does it do?



I'm using an American Power Plus 20 harness to re-wire my car right now. I'm also needing a way to provide power to my megasquirt computer both with the key in the on position and the start position. Help?

Thanks!
Wade