Identify callback control id

I have a masterpage that contains a user control. The usercontrol uses callbacks for various operations. However, every time a callback is issued from the user control it is propagated down to the pages that inherit from the master page. How do I determine the id of the control t开发者_如何转开发hat issued the callback so that I can stop these callbacks from destroying the state of the pages?

Thanks!

---

string control = page.Request.Params.Get("__EVENTTARGET");