An SAP transaction ID (TID) is contained in the ALE wrapper business object and is therefore available as a field in the message tree. You can use transaction ID support to ensure once-only delivery of ALE objects.
The most common reason for using transaction ID support is to ensure once and only once delivery of data. The SAP transaction ID property is always generated by the Adapter Connection wizard.
The SAP transaction ID can be used for cross-referencing with a global unique ID that is created for an outbound event. The global unique ID is something you can create for managing integration scenarios.