US Immigration laws provide a lvariety of nonimmigrant visa categories for different groups of people coming to the US. A nonimmigrant visa normally starts with a letter and followed by a numeric number, almost literally from "A" to Z.
Under each alphebetic letter heading, there could be multiple sub-groups or variations in the general visa category. For example, under the letter "G" which is the nonimmigrant visa symbol for the category of "Foreign Government Officials to International Organizations" based in the United States such as the foreign representatives to the United Nations or other international organizations with a physical presence in the US, there are actually FIVE different sub-categories, namely:
"G" visa category is for Foreign Government Officials to International Organizations, and it has the following sub-classes:
G-1 Visa: Principal resident representative of recognized foreign member government to international organization, and members of immediate family.
G-2 Visa: Other representative of recognized foreign member government to international organization, and members of immediate family.
G-3 Visa: Representative of non-recognized or nonmember government to international organization, and members of immediate family
G-4 Visa: International organization officer or employee, and members of immediate family
G-5 Visa: Attendant, servant, or personal employee of G-1, G-2, G-3, G-4, or members of immediate family