Section 19C. The board shall establish a comprehensive statewide program of regional library service, consisting of regional library systems, which shall not exceed six, for the purpose of providing reference and research services, interlibrary loan, delivery, and other regional services to public, school, academic, and special libraries in the region. For each regional library system, the board shall designate an administrative agency. For such purpose, there shall be an annual appropriation which the board shall apply in the following manner:

(1) Insofar as practicable the board shall enter into an arrangement or arrangements with such public library or libraries in each regional area as it may determine under the terms of which such library or libraries shall supply services or space, equipment, personnel, books, periodicals and other library materials to communities having fewer than twenty-five thousand inhabitants;

[There is no clause (2).]

(3) Any regional library system providing service under an approved plan shall be entitled to receive annually in state aid an amount per capita of its served population per square mile of the area served in accordance with the following schedules:

(4) In addition to the sums provided in clause (3), the Boston public library, as the library of the commonwealth for reference and research services, shall be entitled to receive in state aid the sum of fifty cents for each resident of the commonwealth;

(5) Any employee employed in a position identified as a regional position in a public library which accepts funds under this section shall not be required to comply with residency requirements. For purposes of this section, ''regional position'' shall mean a full-time or part-time position for which at least fifty per cent of the funding is provided by the commonwealth pursuant to this section.