Similar to S.20.03, you can use the S.20.04 Parts with Tabledetails screen to define filter conditions in order to generate more specific commodity codes and to prevent from creating meaningless and needless commodity codes.
To define such a filter do the following:
Select a commodity group and then a commodity part.
Select a table name.
Select a table group.
Assign a table detail.
When now creating a commodity code for this commodity part, you could only select the table details defined on S.20.04 for the selected table and table group.