How to set ignition timing on a Golf?
 

I have a 2001 model 1300 golf.
I want to set the ignition timing, I am using the marks on the flywheel.

There is a notch and there is also a square block that's been cast on the fly wheel, which one do you use to set the timing?
What is the other one for? Is the one TDC and the other where timing must be?