California Code, Health and Safety Code - HSC § 44041

In order to expedite emissions testing and to eliminate errors in the transcription of vehicle data, the department shall, in cooperation with the Department of Motor Vehicles, furnish bar code labels or bar coded documents to all vehicle owners at the time of their vehicle's annual registration renewal. The labels or documents shall contain vehicle identification numbers and other vehicle-specific information, to be determined by the department, which can be recorded by smog check station technicians utilizing the scanning devices required by Section 44036.