Yes, ERP Code is attribute.
It should be manually entered for the top level assembly when viewing the structure in structure manager. For each variant configured structure i want to give different ERP code.
You can have custom occurrence note type as ERP Code.
ERP Code note value can be set in context of your bom window top line.
Same behavior can be achieved, if your ERP code is defined on any of the forms attached under the item or item revision (master forms or custom forms).
If I am selling my product on the basis of ERP code then for different variant configured structure, I have to give different ERP code.
May be it would be helful to us if you can share some snapshots or quick notes on how you are managing you product for different variant configurations. so that we can suggest better option