Markings on converter

The markings may mean something useful, or not. If a supplier made a shipment of bad parts to the factory, they are required to "certify" their stock for "defect free" parts for a minimum of 30 days after the issue was found and they can guarantee the parts shipped after that would not have that defect. This could be a mark for that.

Engineers could also run small batches of parts to see if the new change will affect the assembly/production process. They would also mark the parts so they could identify them during the batch build. If the parts would run through the system without any issues, then the supplier would get the approval to make the change for full production. I used to run these all the time for different parts.