(a) This subchapter is supplemental to all other provisions of state law governing the issuance of bonds by any governmental unit and, except as otherwise provided in this subchapter, the provisions of state law governing the issuance of bonds by any governmental unit shall continue to apply to the issuance by the governmental unit of taxable bonds.
(b) This subchapter does not broaden or otherwise alter any provisions of state law as they relate to the issuance of the bonds the interest on which is, in some manner, exempt or excludable from federal income taxation.
(c) The reference in this subchapter to law providing authority for issuance of bonds means laws now in effect and as hereafter enacted or amended by the General Assembly.
(d) This subchapter does not impugn the validity of any taxable bonds heretofore issued.