MEK1 - Needs to find table of the field

Hello All

Need your help in regards to condition record..

We have some key combination (Access sequence) defined for condition type NAVS...to achieve automatic tax code appearnce in PO.

now one of the key combination in MEK1 is Material/Plant/Import

My question is how to or where to check from where Import field is coming from or maintained. I am looking for a table or any master data from where this Import field is picked up by the system in MEK1.

regards

Yogesh