“S” Endorsement: Required to operate a school bus, or any vehicle that requires a “V”, “A” or “F” endorsement.  In addition to the “S” endorsement a commercial driver license with a “P” endorsement is also required.  Please see CDL Testing Requirements for more information on how to obtain a CDL.
“V” Endorsement: Required to operate a student transportation vehicle transporting students to and from school, including transporting special education students, or any vehicles that requires an “A” or “F” endorsement.  A certificate of safety training (R-360) is also required prior to the issuance of the “V” endorsement.  A certificate may be obtained through school bus company.
“A” Endorsement: Required to operate a student transportation vehicle used in connection with school-sponsored events and activities or other vehicle that requires an “F” endorsement.  Cannot be used to transport students from home to school.
“F” Endorsement: Required to operate a taxi, livery vehicle, service bus, motor bus or motor coach (In addition to the “F” endorsement a CDL with a 'P' endorsement is required on vehicles designed to transport sixteen or more passengers, including the driver.
See Connecticut General Statutes 14-44 for more information.