16 CFR 500.23 - Expression of net quantity of contents in SI Metric units.
(a) The selected multiple or submultiple prefixes for SI metric units shall result in numerical values between 1 and 1000, except that centimeters or millimeters may be used where a length declaration is less than 100 centimeters. For example, “1.96 kg” instead of “1960 g” and “750 mL” instead of “0.75 L”.
(b) The following symbols for SI metric units and none others may be employed in the required net quantity declaration:
Symbols, except for liter, are not capitalized. Periods should not be used after the symbol. Symbols are always written in the singular form.