Packaging Type in Export Declaration

Hello

I like to know how the packaging type in the export declaration document in GTS is populated. SPRO shows GTS packaging type is mapped to packaging type of ECC. Although I could not find the packaging material type assigned in ECC in Material Master for a material, still GTS picks the packaging type for that material.

Can you please let me know the flow from where GTS picks the packaging type, packaging number and the packages..

And issue is that for NE packaging type (Not packed or packaged),my system is populating the item qty as the number of packaging.

Want to know how the system is picking wrong package qty (item quantity) for a NE packaging type.

Thanks

Sudesh