Starter relay wiring

I built an engine run in stand, and used a Chrysler starter relay.

Looking at the relay, I can't for the life of me remember what the "I" spade is for. Do I need to even use the thing?

I know I have to ground one with the "G" spade and the other with the "S" goes to the starter.

So do I need to use the I spade or can I just forget it?

Thanks