The Merchants (3) are required to obtain ZIPFUND's (2) transaction identifier (11) from customers for confirmed purchases.

The write logic also writes priority information in the entry based on other entries having the same transaction identifier.

The transaction receiver is configured to receive from a transaction terminal a transaction identifier for authorization of a proposed transaction.

A secure transaction is carried out by a merchant application which provides details of the customer bank and the transaction amount to a host system (104) and receives a transaction identifier.

The method comprises generating a typified checksum based on a transaction identifier and at least a portion of a packet.

The Xid interface is a Java mapping of the X/Open transaction identifier XID structure.

When information is written into the tracking buffer, write logic writes a corresponding transaction identifier to the first free entry.

A tracking buffer apparatus includes lookup logic configured to locate entries having a transaction identifier corresponding to a received request.

The second server sends, as response (24), to the terminal first data relating to a transaction identifier and a challenge.

If there are still other providers involved in the transaction, then the customer's system sends messages to each of the remaining providers in turn and similarly obtains a transaction identifier from each.

The present invention provides a method and system for transmitting a transaction identifier from a handheld communication device to an Electronic Data Capture (EDC) Device.

The goods are given by the vendor to a common carrier in a package encoded by the vendor with a transaction identifier or a customer object.