The N visa category is reserved for a “child” (who is unmarried and under the age of 21) of an officer or employee, or of a former officer or employee, of a foreign government which is also a member of an international organization (NATO included) under the International Organization & Immunities Act.
In general, N nonimmigrant classification may be granted for up to 3 years with possible 3 years extension (in increments) as long as the petitioner remains a “child.” While holding N visa status, the person is permitted to be employed by obtaining an Employment Authorization Document from USCIS.