Co-Products 
Select this field for a material that is produced during the same process as other basic materials. These items are treated as material credit memos for costing purposes and reduce manufacturing costs.
You can only select an item as a co-product if the following requirements are met:
- Material master record
The Indicator: material can be co-product must be set in the MRP data.
- Bill of material
The material item
- Must have item category Stock item.
- Must not be allocated to an alternative item group.
Special features for maintaining items
The following special points apply to co-products:
- You must enter the component quantity as always a negative value (for example, 3-).
- You cannot set the fixed quantity indicator.
- You cannot maintain discontinuation data.