C visas: This visa for foreigners traveling “in immediate and continous transit” through the USA. In order to be admitted, the foreigner must have sufficient funds and permission to enter a third country.
D visas: this visa is for foreigners working as crew members on airlines and shipping vessels. Normally, crew members are no allowed to remain for more than 29 days and may not be granted extensions or change of status.
NATO visas: This visa is for representative of nations beloning to NATO, their staff, and immediate family.
N Visas: this visa is for parents of an undocumented person who is accorded special immigrant status.