(iii) An offer of employment from a prospective United States employer. A
labor certification is not required for this classification. The offer of
employment shall be in the form of a letter from:
(A) A United States university or institution of higher learning offering
the alien a tenured or tenure-track teaching position in the alien's
academic field;
(B) A United States university or institution of higher learning offering
the alien a permanent research position in the alien's academic field
