What determines the list of action for first Responder?

Question

If I click firstResponder and see all the outlet I saw this pics:

I recognize the name as some of the name of my selectors.

I noticed that

1. The fact that selector is public or not doesn't seem to matter to get into the list
2. I am not sure if the selector need to be IBOutlet or IBAction
3. Some of my new selectors that is IBAction doesn't show up there. Where is the criteria for selectors listed there documented? Did I miss anything?

I want to get rid all that's not necessary.

Actually what should be there anyway? And how do I get rid those?