7 CFR § 29.3619
Rule 18
July 6, 2020
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]