I was going down the same path, about to suggest "quaternary" (also "quartary"), but the generated code reveals the rationale: there are 3 (not 4) in the ordere

I was going down the same path, about to suggest "quaternary" (also "quartary"), but the generated code reveals the rationale: there are 3 (not 4) in the ordered listing, plus an accent color. The explanation before the generator just happens to mention the accent color amidst mentioning the three ordered colors.