Xantrex 458 Freedom "filtered" modified sine???

A modified sine wave inverter in the old days was basically a square wave. There could be any manner of filtering done to the wave to make it "closer" to a pure sine wave. Also, there may be any number of "steps" involved in the waveform. The more steps the closer it will resemble and actual sine wave. The less steps the more it will resemble a square wave.
Do you know anyone with an oscilloscope? They could show you a picture of your wave form output.