The idea was to demonstrate to people interested in a quick, approximate estimate of the amount of flue gas being emitted to the atmosphere by a fossil-fueled heater/furnace/power plant steam generator/ etc. that they could use 11,600 to 12,700 scf per million Btu of fuel burned (where scf means cubic feet of flue gas at 60 °F and 1 atmosphere) ... and probably be within 10% of the true value for their specific fuel.
That range of values translates to 295 to 320 Nm3 per GJ of fuel burned (where Nm3 means Normal cubic metres of flue gas at 0 °C and 1 atmosphere).
Who is interested in such data? Anyone interested in performing an air pollution modeling study of the flue gases from one or more of their plant's fired heaters. Also, anyone thinking of installing some type of pollution control system on their flue gases and needing to know the flue gas emission rate in order to size the pollution control equipment. Or anyone wanting to recover some of the waste heat being emitted with those flue gases.