T - Endorsement, Required for double or triple trailers.
P - Endorsement,Required for vehicles with a designed capacity to transport 16 or more passengers, including the driver.
N - Endorsement,Required for a tank vehicle designed to transport liquid or gaseous materials with a rated capacity of 1,000 gallons or more.
H - Endorsement,Required when transporting hazardous material in any amount requiring the display of placards by 49 CFR, part 172, subpart F.
X - Endorsement,Combines the N and H endorsements for a single endorsement allowing operation of tank vehicles transporting liquid or gaseous hazardous material.