Any such resolution or agreement may provide that all or any part of the revenue of the district shall be paid into a special fund, and may set forth all the terms and conditions on which such special fund is to be collected, held and disposed of, whether partly or wholly for the benefit of the holders of such revenue debentures, notes, warrants, or other evidences of indebtedness. Provision may be made that such special fund shall be held by depositories designated or described in such resolution or agreement.