Travelling - When do you present your AP?

[pmchi]

Hi,

I was wondering if anyone can offer any experience on travelling with Advance Parole. At what point do you present your Advance Parole document (or card)? Do they check you on the way out of the US, or only on return?
What if you lose your document/card while abroad?

[scientist2016]

Your card is checked only on the way in. US does not check on exit.