7 CFR § 29.3028
Grademark
July 6, 2020
A grademark normally consists of three symbols which indicate group, quality, and color. A letter is used to indicate group, a number to indicate quality, and a letter or letters to indicate color. For example, C2F means Lugs, second quality, and tan color.
[24 FR 8771, Oct. 29, 1959. Redesignated at 49 FR 16757, Apr. 20, 1984]