This section reviews commonly used ways of representing costs (fixed and variable, direct and indirect), and one less commonly used way (engineered and discretionary). If you are already familiar with the concepts of variable and fixed costs and break-even charts, then start at section 3.3. Bear in mind that the total cost picture is always the same; the different ways of representing them are simply different ways of ‘cutting the cake’. Let us look at the total cost as a cube instead of a cake. Then the three different ways of representing costs can be shown as different ways of cutting up the cube (Figure 3.2).