Rule 18
Primary source
Verbatim text below is from the Electronic Code of Federal Regulations (eCFR), a public-domain U.S. government work. Always verify the current version with the eCFR before relying on it for any legal matter.
Full Text
Any lot of tobacco of the B, C, or X groups shall be classified as “mixed” and designated by the color symbol “M” when it is not green but contains (a) over 30 percent of colors distinctly different from the major color or (b) over 30 percent of a combination of variegated and colors distinctly different from the major color mingled together.
[51 FR 40408, Nov. 7, 1986]
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.