Apple pay and pass integration

Hello,

does anyone know, how to check and transmit message from loyalty pass in your wallet when paying with apple pay through the payment terminal? e.g: You are buying shoes from store and when you are paying with apple pay and at the same time it checks and passes a message(id or something) from your loyalty pass in your wallet. ("One tap" experience, like it was said here https://developer.apple.com/videos/play/wwdc2016/704/?time=247)

I only know, I need this NFC certificate and add nfc payload to a pass.

How does it work and what else it takes to get that message from a pass?