Indiana Code Title 8. Utilities and Transportation § 8-1-11.1-21

Sec. 21. Such revenue obligations shall be secured by a pledge of the unobligated income and revenues of any one (1) or more of the utility properties of the department of public utilities.  In addition, the board of directors for utilities may in its discretion secure the payment of such revenue obligations by a mortgage upon the property of the particular utility for whose benefit the proceeds of the revenue obligations are to be used.  In authorizing the issuance of such obligations for any particular property or properties, the board of directors for utilities of the department of public utilities may limit the amount of such obligations that may be issued as a first lien and charge against such property or properties and the income and revenues therefrom, or such board of directors for utilities may authorize the issuance from time to time thereafter of additional obligations secured by the same pledge or lien to provide funds for the completion of the property, properties, betterments, improvements, extensions or additions thereto, on account of which the original obligations were issued, or to provide funds to pay the cost of additional utility properties, betterments, improvements, extensions or additions thereto, or for both such purposes.  Such additional obligations shall be issued on such terms and conditions as such board may determine, and may be secured equally and ratably, without preference, priority or distinction, with the original issue of obligations or may be made junior thereto.