Most corporations use Raised Lettering to identify the foundry with the year/month/day that the casting was poured and part number of the casting. This is to identify the casting batch incase of material quality issues or some other casting defect. That way if you have to scrap the casting do to a defect, you do not have to scrap a large batch casting. That way you would only scrap those casting from the pour, if it was a material defect or some other casting defect.