Final answer:
Very thin stock is specified by using appropriate units for the material's thickness, such as millimeters for a thin aluminum plate and centimeters for tissue in scientific contexts.
Step-by-step explanation:
Very thin stock is specified using units that are appropriate to the scale of the material's thickness. Examples of different scales include a sheet of paper, which is typically around 0.1 mm thick, a few cm of air which doesn't have a physical thickness but can be considered in contexts like wind tunnels or aerodynamics, and fractions of a mm of tissue which is pertinent in medical imaging and treatment planning. In industrial contexts, a thin aluminum plate might be measured in millimeters or fractions thereof, and when working with biological materials, such as tens of cm of tissue, the specifications would relate to medical or scientific contexts where such measurements are relevant.