National Safety Code (NSC) Standard 13 prescribes daily trip inspection requirements. According to Standard 13, a vehicle with a major defect may not be driven until the defect is repaired. Examples of major defects are a broken seatbelt, an inoperative parking or emergency brake, and an inoperative rearmost turn signal lamp. A missing fuel tank cap is considered a minor defect unless fuel is leaking from the tank, which is considered a major defect.