Diplomatic Visa 

To be issued an A-1 diplomatic visa you must be: a Head of State; a member of a Royal Family; a Governor General; a Cabinet Member; a Justice of the Highest Court; a Presiding Member of the Legislature; an Ambassador; or a Military officer at or above the rank of brigadier general. You must also hold a diplomatic passport from your country.

To be issued an A-2 visa you must be an accredited official or employee of a foreign government and their immediate families. 

To be issued an A-3 visa you must be an attendant, servant, or personal employee and a member of their immediate families.