Not familiar with this call out.

[[Da...]]

Not sure what the 0.28 MAX ON R means. Any help would be appreciated !

[[Ma...]]

Is anywhere on drawing written "R"? I don't think, that it would have something in common with roughness ( like Ra max 0.28 on R face )

[[Da...]]

It seems to me that you have a 0.28 MAX on the Radius at the edge of the Ø 31.687. It is difficult to tell based only on the callout and not able to see the drawing or the part.

[[De...]]

Simplified your radial dimensional tolerance is 0.00, +.28. This callout is commonly used for features such as depths of holes, lengths of threads, comer radii, & chamfers. In my experience the callout on your print is traditionally used as a courtesy to the operator and machinist.

[[Wo...]]

Isn't IE2261 the stock removal specification for catterpillar?

I think it tells you that after heat treating you can only remove 0.28mm on the radius max, but I would have to lookup the spec, because it has been a while since I've looked at it.

[[Wo...]]

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Just looked up the spec, it's definitely this. It even has an example almost exactly like yours - "0.33 MAX ON R"