Fact tables that expose the full equation of profit are among the most powerful deliverables of an enterprise DW/BI system. The equation of profit is (revenue) – (costs) = (profit). Fact tables ideally implement the profit equation at the grain of the atomic revenue transaction and contain many components of cost. Because these tables are at the atomic grain, numerous rollups are possible, including customer profitability, product profitability, promotion profitability, channel profitability, and others. However, these fact tables are difficult to build because the cost components must be allocated from their original sources to the fact table’s grain. This allocation step is often a major ETL subsystem and is a politically charged step that requires high- level executive support.  For these reasons, profit and loss fact tables are typically not tackled during the early implementation phases of a DW/BI program.