Subject to subsection (c) of this section, the special fund for the development district, the RISE zone, or the sustainable community may be used for any of the following purposes as determined by the governing body of the political subdivision: a purpose specified in § 12–207 of this subtitle; accumulated to pay debt service on bonds to be issued later; payment or reimbursement of debt service, or payments under an agreement described in subsection (b) of this section, that the political subdivision is obliged under a general or limited obligation to pay, or has paid, on or relating to bonds issued by the State, a political subdivision, or the revenue authority of Prince George’s County if the proceeds were used for a purpose specified in § 12–207 of this subtitle; or payment to the political subdivision for any other legal purpose. Subject to paragraph (2) of this subsection, the political subdivision that has created a special fund for a development district, a RISE zone, or a sustainable community may pledge under an agreement that amounts deposited to the special fund shall be paid over to secure payment on MEDCO obligations. The agreement shall: be in writing; be executed by the political subdivision making the pledge, the Maryland Economic Development Corporation, and the other persons that the governing body of the political subdivision determines; and run to the benefit of and be enforceable on behalf of the holders of the MEDCO obligations secured by the agreement. If bonds are outstanding with respect to a development district, a RISE zone, or a sustainable community, the special fund may be used as described in subsection (a) of this section in any fiscal year only if: the balance of the special fund exceeds the unpaid debt service payable on the bonds in the fiscal year; and the special fund is not restricted so as to prohibit the use. The issuance of bonds pledging the full faith and credit of the political subdivision shall comply with appropriate county or municipal charter requirements.