Stamping on cylinder block

[jpepper]

I recently dismantled a 63 R1 core engine. By the engine number stamping at the front is what looks like a Heinz ketchup logo outline. Does anyone know if it means something? I am guessing that it might be an inspectors stamp but could be wrong. Any thoughts? Sorry that the image is upside down. I did not see a way to edit it.

[RadioRoy]

That symbol is called a keystone.

[studegary]

That symbol is called a keystone.

I believe that it meant an extra measurement/inspection procedure before it left the factory.

[Skip Lackie]

The almost-invisible number inside it identified the inspector.

[jpepper]

That is what I thought. Thanks all.