The department may from time to time or at any time sell or exchange refunding bonds for the purpose of retiring, paying, or refunding either all or part of the outstanding revenue bonds, or of one or more series thereof, as it deems advisable. Such refunding bonds may be issued and delivered as outstanding revenue bonds to be refunded thereby mature or are about to mature or are subject to call or redemption, or if the retirement thereof has been assured by consent of the holders thereof. Refunding bonds may be delivered in whole or in part in exchange for outstanding revenue bonds with the consent of such holders.
Ca. Mil. and Vet. Code § 487.3