When summing costs to measure non-market output, the 1993 SNA recommends that the value of the services provided by a producer's own non-financial assets should be measured as consumption of fixed capital. This means that neither a return on capital to these assets nor, equivalently, an opportunity cost of capital is recognized. This leads to an inconsistency with the rental that would have to be paid if the assets were rented. Should the SNA recommendation be changed and the cost of consumption of fixed capital be replaced with capital services (consumption of fixed capital, expected holding gains/ losses and the capital or interest costs)?