real-interest-only (RIO): 1. One of the primary payment streams on the inflation-indexed instruments, which equals the real rate times the accrued principal value (or the NPO strip plus the AIO strip). 2. The payment stream that becomes a byproduct when the RPO payment stream is used to provide the present value assets for the issuance of the private currency. 3. The byproduct that can be sold by the sponsor to cover expenses and a reasonable profit. 4. The means by which the sponsor can sell the private currency on a wholesale basis like any other product.