On the S.20.02 Tablenames with Details screen, query for the table and group. The table names are defined on A.50.02, and the table groups on S.20.01.
In the second (Details) block, define the table details. The table detail codes will be part of the commodity code, and the short desc and description will become part of the commodity code description. The table details provide more specific information, for example, for the table group Carbon Steel in the Material table you could define the detail: Carbon Steel A106 Grade B, CS A106 B.