...
SubmitDTSData( transData : TransData,
...
dtsData : DTSData)
The load message contains, for each arrival airport, information about what actually is on board the aircraft that has the arrival airport as the final destination.
For a single leg flight there will be only one LoadDestinationIATA airport, and only one LoadDestinationData as defined in DTSDataSubmits the DTS (Daily Traffic Survey) data for further processing.