The Zero Point Oscillator is not your typical analog VCO or even your standard Thru-Zero FM VCO for that matter.
The core of the ZPO was developed through countless hours of experimentation involving Through-Zero modulation techniques.
Through-Zero FM is a form of frequency modulation that produces much deeper and useful FM tones than a typical VCO can accomplish.
New techniques have been discovered that not only improve the performance of TZFM, but also grant additional benefits as will be explained.
More info here: Steady State Fate | Zero Point Oscillator (ZPO)