It all depends on what Network protocol is being used.
The transaction data will be encrypted and wrapped up into a data packet according to whatever protocol is being being used.
Typically a network packet will have a delimiter - so we know where the packet starts, an address of some sort, some control information, maybe a length field, type of packet field, the data and some check digits.
I'll try to make my Question more clear. I am trying create a standard format for the packet that is sent from merchant to a bank. I assume the header of the packet should hold the information such as correspondent bank code, country code etc. . . The packet will use Secure Socket Layer if it will help. Sry i have very little knowledge about these kind of things. Any help is appreciated. Thx
KoliPoki
If my memory serves me correctly there is an ISO standard for these type of mesages.
I only know about the format of messages between the banks via credit/debit card processors eg. VISA, Mastercard so can't explicitly comment about Merchant -> Bank format. However, I would think there are similar standards.
I would suggest contacting some of the manufacturers of EPOS terminals - Thales, Ingenico etc and the Technical department of some of the banks. However, unless you have good reason for wanting to know they are likely to be very cagey about providing information.