(a)(1) Except as provided in subsection (b) of this section, a page serving during an academic year - (A) shall be in the eleventh grade; and (B) shall serve for one full semester or two full semesters. (2) Except as provided in subsection (b) of this section, a page serving during the summer term - (A) shall have completed the tenth grade; and (B) shall not have begun the twelfth grade. (b)(1) An unforeseen vacancy occurring in a page position during an academic year may be filled, except that no appointment may be made under this paragraph for service to begin on or after October 1 with respect to the first semester or on or after March 1 with respect to the second semester. (2) An individual who has served as a congressional page at any time during each of any three semesters or terms, as the case may be, shall not be eligible to serve as a page.