In Reply to: FL posted by Bruce (VA) on July 24, 2020 at 10:57:12:
The tags were attached to the molds that made the sand forms for casting the blocks. The tags were attached with screws, which would allow changing the tags each day, if not more or less frequently. The tags were produced with a machine that worked like a Dymo label maker. This meant that the tags could be changed very easily.
Many blocks could be cast using the same mold. While they suffered some wear/damage in use, they were quite durable. The tags were changed to keep track of production, quality control, and inventory. It makes sense that the tag would be changed daily, given that the code stamped in them referred to specific days.