Mandatory
This field specifies the reference number assigned by the Sender to unambiguously identify the message.
This field must not start or end with a slash '/' and must not contain two consecutive slashes '//' (Error code(s): T26).
The reference assigned to a message is used for cross-referencing purposes in subsequent messages, such as following MT 300s and statement messages, as well as queries. It is therefore essential for the identification of the original MT 300 sent that this reference is unique.