Indiana Code Title 36. Local Government § 36-9-11-20

Sec. 20. (a) This subsection applies only to cities.  All or part of the gross revenues, or of the net revenues remaining after the payment of the cost of operation, maintenance, and repair, may be pledged to the payment of the principal of and interest on the revenue bonds and the accumulation and maintenance of the reserve for the bonds, in the manner and to the extent provided in the ordinance or ordinances authorizing the issuance of the revenue bonds.  The ordinance or ordinances authorizing the issuance of revenue bonds also may provide for a pledge of all or a designated part of the gross or net revenues derived from:

to the payment of principal of and interest on revenue bonds issued or to be issued under this chapter, and to the accumulation and maintenance of the reserve for the bonds.  The extent and the manner of making the pledge may be provided in the ordinance or ordinances authorizing the issuance of bonds.

(b) This subsection applies only to towns.  An ordinance authorizing the issuance of revenue bonds for parking facilities may provide for a pledge of all or a designated part of the unobligated net revenues derived from other parking facilities, parking meters, or parking mechanisms, to the extent required to maintain the parking sinking fund established under section 19 of this chapter at the minimum level.