Hi Arjun,
It sounds like you are trying to carry out a technical task without any knowledge of the process. That's not a good idea, in my opinion. You should find someone who can explain what sort of data those fields should contain.
It would help to know what sort of Customs Declaration you are trying to map, and for what reason. I suppose, like me, that most readers won't know what the AIDA system is or does.
I guess the "Transportation Plate Number" refers to a vehicle? If so, you should probably be looking at segment /SAPSLL/E2CCEHD_TPR, where you will find several "Means of Transport Indicators" that can correspond to the various vehicles involved in the international journey.
As for the "Regime Code", does AIDA have a list of possible values ("code list")? If so, perhaps you could provide examples that might help to point to the equivalent data in GTS?
Regards,
Dave