MÉXICO

(A) Prefix B was used in Baja California. Prefix G was used in Guanajuato and Guerrero.

(B) Prefix P was used in Puebla and San Luis Potosí

(C) Prefix Y was used in Campeche, Colima, Morelos and Yucatán

(B) ONAPPAFA (Organización Nacional de Proteccion al Patrimonio Familiar - National Organization to Family Heritage) like ANAPROMEX issue provisional plates to owners of illegally imported US sources vehicles, which is often a "poor man's way" to obtain some form of documentation.
I am assuming ANAPPAFA (numbers "50817" and "86500") belongs in this group.

(C) ODEPAFA (Organización de Defensa del Patrimonio Familiar - Organization for the Defense of Family Heritage) is an association that assists people with the legalization of imported vehicles.

(D) UDC (Union Democrática Campesina - Democractic Peasant Union) is an organization known for its assistance with vehicle regularization and other services, particularly for those in rural and migrant communities.

SAF = Secretaria del Autotransporte Federal - Secretary of Federal Motor Transportation

SAT = Servicio de Administración Tributaria - Service Tax Administration

SCT = Secretaria de Comunicaciónes y Transportes - Communications and Transportion Secretary

SET = Servicio Exclusivo de Turismo - Exclusive Tourism Service

Beginning in 1972, México started issuing special plates for privately owned vehicles in all of Baja California and Baja California Sur and for privately owned vehicles registered in the 20 mile border zone with the United States in Chihuahua, Coahuila, Sonora and Tamaulípas.

In the end-1990's, other vehicle classes also received border zone plates.

These plates are different from non-border zone plates in their color and numbering schemes.

Non-Passenger Border Zone License Plates

Prototype License Plates - México

Summer and Winter Olympic and Paralympic Games