An indenture may include a clause relating to the bonds issued pursuant to the indenture requiring the regents to hold, or cause to be held, in trust the revenues, or any part of revenues, pledged to the payment of such bonds and the interest on such bonds, or to any reserve or other fund created for the further protection of the bonds, and to apply such revenues, or part of revenues, or cause them to be applied only as provided in the indenture.