Octane
Minimum octane is not regulated federally by the Environmental Protection Agency: that said, labeling accuracy requirements set by the Federal Trade Commission still apply.
Although minimum octane is not regulated federally, it is regulated, at the state level, by the vast majority of states in the U.S. These states either set explicit limits via regulation, or adopt, by reference, the limits set by the National Institute of Standards and Technology Handbook 30. (but not always) to conform to 87 AKI for regular grade, 89 AKI for midgrade, and 91 AKI for premium.