Question Animation Event Objects

This isn't so much an issue I'm having as something I'm just a little confused about.

I'm using a model that has some read-only animations with it. I managed to edit one of the animations; I wanted it to fire a projectile partway through the animation. I'm generally familiar with the process, but it looked a little different since I couldn't do it through the animation window.

Anyway, I dragged a script into the object field that looks like this:

Code (CSharp):

1. public class ShootingScript: MonoBehaviour
2. {
3.   void Update()
4.   {
5.     if (Input.GetKeyDown"s") Shoot();
6.   }
7.  
8.   public void Shoot() {}
9.  
10.   public void Die() {}
11.  
12. }

I wrote that code for the example, it's not my actual code.

I didn't specify which function to call, but it successfully calls shoot and fires the projectile I wanted (even though this script isn't attached to anything). It works, so I'm not complaining, but can someone explain to me why it's working?