But still it is patented.It's not really "proprietary" in any meaningful sense. It's just some imaginary letters they made up to describe a Class B amp with an optimized bias setting. It's a textbook Doug Self "Blameless" design, which I assume is essentially the exact same topology he spells out in his power amplifier book, which is focused on identifying sources of distortion and eliminating them. No secret sauce, just a solid, well-engineered design.
https://www.ipo.gov.uk/p-ipsum/Case/ApplicationNumber/GB0505024.0