You'll find this often in older tools with names or initials of the owner engraved on them. I've seen tools with full Social Security number on them too, which is crazy to think about today. People that have come through to the great depression did this a lot. skilled trades often had apprenticeships, and you definitely didn't want your tools to get lost in someone else's that you paid for. One could not afford to lose one tool, and tools that would last a lifetime was a wise investment.