Great, thanks for the explanation. No wonder I couldn't find it online...it sounds pretty complicated.

As it is, I should have luggage checked through to Italy (which I believe is a Schengen country), and since I'll be arriving on a NW flight and transferring to KLM, I should have boarding pass when I arrive in AMS.

I have a relatively short connection in AMS...do I HAVE to go through customs there, or can I just sit on it and wait and do the whole thing in Italy?

If it turns out that I don't check luggage, and everything is on my person, does that change the answer?

Thanks again