Structure or Internal table

Hi,

I am trying to create a function module to extract transaction data from R/3. Here, my question is: How do I transfer data from Interface table(E_T_DATA) to BW. Do I need to create(Define) an <b>internal table</b> in function module? or do I need to create a <b>Structure</b> in Data dictionary(SE11) and then define E_T_DATA LIKE (structure name or Internal table name)in the table parameters tab. I appreciate your help with points.

Thanks,

Rao.