Why is the PCB part number traditionally on a copper layer?

I notice that each design file from the supplier contains part number. It seems that it become a common habit in PCB design field. Just be curious about the reason.

PCB Design
November 20, 2023

The designer places marks on copper layer for easy identification after the artwork is prepared. Part number on the copper layer will last till the PCB lasts itself.

#PCB Design

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

Oliver Smith

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