Optional
This field identifies the Sender of the message.
Field 51A is only valid in FileAct
(Error code(s): D63).
IFT
At least the first eight characters of the BIC in this field must be identical to the originator of this FileAct
message.
IFT
The content of field 20 Sender's reference together with the content of this field provides the file identification which is to be used in the case of queries, cancellations, etc.