California Code, Health and Safety Code - HSC § 114303

(a) Employee entrance doors to food preparation areas shall be self-closing and kept closed when not in use.

(b) The mobile food facility, and all equipment and utensils shall be protected from potential contamination, and kept clean, in good repair, and free of vermin.

(c) During transportation, storage, and operation of a mobile food facility, food, food-contact surfaces, and utensils shall be protected from contamination.

(d) The permitholder of an unenclosed mobile food facility handling nonprepackaged food shall develop and follow written operational procedures for food handling and the cleaning and sanitizing of food-contact surfaces and utensils. The enforcement agency shall review and approve the procedures prior to implementation and an approved copy shall be kept on the mobile food facility during periods of operation.