One of my Jewish Customers was getting ready to expand his business when I stopped by with the floor plans for the Fire Alarm to show him what the city was going to require. while we where reviewing the plans his mom was sitting in the office as she came by a couple days a week and they would go to lunch.
She told me the tale of a friend of theirs who attended the same Synagogue and was a Holocaust Survivor who immigrated to the US became a Professional Engineer for Westinghouse Electric Corporation here in Pittsburgh.
As a way at getting back at the Nazis on every plan for Generators ,Switch Gear and Motors etc that where going overseas to help rebuild Germany. He would put a large print Circle with a J in it next to his name where he sealed the documents and in the Foot Notes and Specifications Lists as well to show the Germans that this plan was designed by a Jew.
As a direct way to get back in there faces , that a Jew had designed this plan.
Now is the story true . I believe so and very plausible as there are often all kind of secret identifying marks on prints to tell when copies are made or even to insult another engineer or plan reviewer .
I saw the J circle a few times on prints on overseas equipment plans I have looked at when doing research on repairing old machinery and the engineer had a Jewish name.
So if it is true it was one mans way of getting revenge against the nazis .