Synthesised Sine wave VS Modified Square Wave inverters

[edsys89]

I am to contrast the difference between modified square wave, and synthesized sine wave inverter outputs.

Am I to understand, that a modified square wave output is like a square wave, but the transtion to current flow in the other direction is delayed some at the zero point. This is to give it the same RMS value as true sine wave ac power.

Furthermore, a synthesised sine wave is shaped more like a sine wave but still made of "square blocks" by switching.

Am I on the right track? Is the RMS value of a synthesised sine wave found by multiplying the peak value by 0.707?

 

[Redbelly98]

A modified square wave is given by the red curve here:
http://www.pcguide.com/ref/power/ext/ups/funcOutput-c.html

I'm not sure about the details of a synthesized sine wave.