Readers might question what price has been paid for this relaxation of restrictions. The answer is almost nothing. So long as the analyst pro
duces forecasts, such that, all future changes in book value arise either
from earnings, capital contributions, or dividends, the relation in expres sion (6) holds, that is, the analyst must apply clean surplus accounting for future periods' forecasts. Even if the firm's current book value contains "dirty surplus," the relation in expression (6) will hold so long as fore casted changes in book value are faithful to the clean surplus relation.