Thanks for finding this. Can't take the credit for this, as Jim is the one who found this
As to the tool inserts, the world standard to define the dimensions of inserts is by using the inscribed circle, (except for parallelogram shaped inserts). It is coded in the number of eights of an inch. It is usually a sequence of three numbers along with insert thickness and tip radius. In metric system the insert is defined by the cutting length in mm along with thickness and tip radius. Machinery's Handbook has a good description of the American standard.