xml tag for payment file - for delivery channel code.

What is the xml tag for payment file - for delivery channel code.

We created a new delivery channel code and attached it to a supplier site as payment attribute.

1) How to find the delivery channel linking to the supplier site in the database ( table link between supplier site and delivery channel code)
2) when we map it to the payment file, for generating payment format with the delivery channel code, what is the "tag" to be used for generating the payment file with the delivery channel code.

e.g. Like for payment amount, we have Payment Amount, what is it for "Delivery channel code".