how lines of billable activity are populated in the interface staging area for customer through Bill

Hi,

    Can someone explain on how the lines of billable activity are populated in the interface staging area for customer through Bill by Identifier. So the Bill Lines will go as different lines based on Bill by Identifier? or will it go as a one header with lines associated with it in Billing Interface.

E.g: Bill By Identifier - "Order" and "Ship to" has 2 lines for same customer - then how will it process billing interface for these lines as one whole header with lines or seperate lines.

Regards

Vishnu