The plate is part of its history.
Some years ago I purchased a milling machine. It was in pretty good shape, other than the paint job the seller had applied. I think it was latex house paint mixed with kitty litter. It was remarkably resistant to paint stripper, scrapers, abrasives, and other tools... it took a while to get the thing cleaned up.
Under the thick layer of ick was a brass plate riveted to the column, stating it had been registered as a national asset by the United States War Department. That would have been during World War II.
After removing and carefully cleaning the plate, I riveted it back on.