If you are designing an addition to a complicated, large building that pre-dates modern codes, you might be asked to prove that exits are adequate. The method that worked for us in this scenario was this: show the results of our calculations on a floor plan by giving the occupant load of each space, the capacity of corridors and stairs, and the capacity of the exit doors. See the enlargeable legend to the left.
The building in question had six different levels including a basement and a 'mezzanine'. Previous additions had also obscured the exit strategy. The drawing below is downloadable as a PDF for better viewing.
The first effort was a table to show all this information but it was impossible to follow. Once we hit on this diagrammatic approach, we had the extra benefit that the code official could spot check us very easily. The result was that the plan was accepted once we reviewed the process and how to interpret the diagram. The original diagram was also color-coded by hand to show where the numbers came from. A color plotter would have eliminated that work.