Order or Invoice number

[iluvar]

Hi,

I'm developing a payment module and I need some help.

After the order confirmation the customer is redirected to a payment gateway site where he enters card data. Also some order information is post-ed to payment gateway, like amount, merchant data...and order_id - some unique identifier that connects to this order/invoice. Is there such identification. I looked at payment class and order class but there are no id's there.

Also if anyone know if there is some documentation on payment module developement.

 

Thanks !