Penman (2007a: 36-7) identifies two accounting models in current usage. The first computes accounting profit as the difference between the value of outputs sold and the cost of inputs necessary to create the products sold (the matching concept). The second takes the fair value of assets (less liabilities) at the beginning of the period away from the fair value at the end of the period. Following the four slices methodology, the first is used to place a value on activities that transform inputs into outputs to generate currently consumable product (ESTA and CUVI) and the second for promises and other speculative

activities where value is based upon (changing) future expectations (NVP and GOV).