California Code, Business and Professions Code - BPC § 13570

(a) A manufacturer, blender, agent, jobber, consignment agent, or distributor who distributes motor vehicle fuel that contains at least 1 percent alcohol by volume, shall state on an invoice, bill of lading, shipping paper, or other documentation used in normal and customary business practices, the percentage of alcohol, the type of alcohol, and, except in documentation certifying the octane rating of gasoline as required by federal law, the minimum antiknock index number, as defined in subdivision (q) of Section 13400, of the products distributed.

(b) If a motor vehicle fuel product contains less than 10 percent ethanol, a statement in the documentation that the product “contains up to 10% ethanol” meets the requirement of subdivision (a) that it state the percentage of ethanol.

(c) This section, as it relates to certification of the minimum antiknock index number, applies to all motor vehicle gasoline distributed.