How does Xcode's jump to (symbol) work?

Question

The keyboard shortcut to jump to a particular line in Xcode is Cmd+L

Typing in line number easily works, but what is the "symbol" in "Type Line Number or Symbol"? I tried typing selector names, variable names, nothing seems to work. Anybody knows what the "symbol" here is referring to and how to use it?

Answer 1

I think this feature is not working and will not, ever. In the upcoming Xcode 4.5 you will see just "Type Line Number" without the "or Symbol" part.

This very same question has been filed to Apple, but without answers.