The passenger endorsement is the first of the two that require a demonstration. § 383.117 says an applicant must satisfy both a knowledge and a skills requirement. The knowledge covers proper procedures for loading and unloading passengers; proper use of emergency exits, including push-out windows; proper responses to emergency situations such as fires and unruly passengers; proper procedures at railroad-highway grade crossings and drawbridges; proper braking procedures; and operating practices not otherwise specified. The skills half carries a condition that decides what the endorsement is worth: under § 383.117(b), to obtain a passenger endorsement applicable to a specific vehicle class, the applicant must take the skills test in a passenger vehicle satisfying the requirements of that vehicle group as § 383.91 defines it.

School bus is not a parallel endorsement but a further one. § 383.123(a) sets three requirements, and the first is to qualify for the passenger endorsement — passing its knowledge and skills tests. On top of that comes a knowledge test covering loading and unloading children, including the safe operation of stop signal devices, external mirror systems, flashing lights and the other warning and passenger safety devices required for school buses by State or Federal law; emergency exits and procedures for safely evacuating passengers; and the State and Federal laws and regulations on safely traversing railroad-highway grade crossings. A driver cannot reach the school bus endorsement without passing through the passenger one.

The hazardous materials endorsement is unlike the rest in scope, and the honest way to describe it is that it reaches outside this rulebook. § 383.121 requires the applicant to have such knowledge as is required of a driver of a hazardous-materials-laden vehicle, drawn from information contained in 49 CFR parts 171, 172, 173, 177, 178 and 397. It then enumerates the subjects: the hazardous materials regulations, including the hazardous materials table, shipping paper requirements, marking, labeling, placarding requirements, packaging, definitions and preparation, other regulated material, reporting hazardous materials accidents, and tunnels and railroad crossings; and hazardous materials handling, including forbidden materials and packages, loading and unloading, cargo segregation, passenger-carrying buses and hazardous materials, attendance of vehicles, and parking. It is a knowledge test under § 383.93(c), but the body of material behind it is the largest of any endorsement here.