1940's Press Material Call-Out

[NB02]

I'm not sure if this is the correct place to ask this or not so bare with me. We have an 1940's extrusion press at work and looking at some of the original drawings I have a questions on how the material is called. It states the material like I have seen normally seen on old drawing like CS=cast steel,CI=cast iron,FS=forged steel etc for the type but then it calls out a material proprieties which I assume is either yield of tensile strength of the material. The issue I am having is that I have never seen a material property called out as such. It is "TS/□"" I know what the"□"" is, as in square inch but have never seen it TS? Could it be tons, short or long? It calls out 5 TS/□" for CI which would be in the ball park it just seems foreign to me.

Has anyone else run across this?

Thanks,

NB