Commodity groups are maintained on the S.10.02 Commodity Groups screen.
To create a new group, enter the group name in the Group field and the group descriptions in the Short Desc and Description fields. Select the commodity rule from the LOV in the Rule field and the standard from the LOV in the Standard field. The standards are defined on the A.10.05 Standards screen.
If you want to assign the object parameter on the group level, you must open this screen again after defining the object parameter, and select the object parameter from the LOV in the Object field.