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Engine load
Also known as relative cylinder charge. It represents the percentage of air (compared to standard density) in each of the cylinders. 100% load means each cylinder has the mass of air as an equivalent volume at standard density. Ingested air mass is calculated from MAF value (mass/time) divided by RPM (1/time), divided by two to yield a mass. Standard mass is calculated by engine displacement (volume) times standard density (mass/volume). The ratio of the two masses is load. It is used in real time to determine all other values including boost, timing, and fueling.
Load = \frac{mass_{ingested}}{mass_{standard}}
mass_{ingested}[g] = \frac{MAF[g/sec] \times 60[sec/min]}{RPM[1/min] \times \frac{1}{2}}
mass_{standard}[g] = displacement[cc] \times 0.00122521[g/cc]
Engine load specified
The maximum target load based on programmed values; generally depends only on RPM.
Engine load corrected specified
Adjusted maximum target load based upon a number of internal and external values, two externals being ambient temperature and pressure. Instantaneous ignition retard due to knock control might also affect maximum specified load. Internals are usually due to engine wear trims.
Requested load
Target load based on the accelerator pedal position. It is capped by engine load corrected specified and will never exceed that value.