For purposes of statutes governing schools:
(1) Affiliated school system means the high school district and the Class I districts or portions of Class I districts affiliated with such high school district;
(2) Affiliation or affiliation of school districts means an ongoing association of a Class I district or portion thereof not a part of a Class VI district with one or more existing Class II, III, IV, or V districts for the purpose of (a) providing a high school program serving the Class I district students and (b) maintaining tax support to finance such program. The services provided may include student transportation; and
(3) Class VI school system means a Class VI school district and each Class I school district or portion thereof which is part of the Class VI district.