What does it mean to have two size values labeled on a part part in a machining shop drawing? Which value? Is it all metric or imperial?

First of all, there is nothing wrong with not labeling the size φ in the drawing, because it is not a diameter size. My understanding is for reference only: the size of the left side of the illustration, the designer gave two limit size (value in inches, 1 inch = 25.4mm) that is, the size of 2.86 inches - 2.92 inches, converted to metric system is 72.644mm - 74.168mm. -If the basic size is required, it can be set artificially. For example, the original size can be set to 3 (unit: inch) after the conversion of the size can be set to 74 (unit: mm).