Validation of bonds. Exchange or sale of bonds; use of proceeds. Establishment of sinking fund for unsurrendered bonds. Limitations on issue and use of bonds and proceeds. Powers and duties of officials as to bonds, taxes, and sinking funds. Interest on bonds. When subpart applicable to independent school districts. Construction of subpart against impairment of outstanding bonds.SUBPART 3 Sec. 20-2-501 through 20-2-503. [Reserved].