That's what the PD standard basically is at core. It tucks on other things, too, like negotiating alternate modes, USB data roles, power roles, role swaps, etc.

That's what the PD standard basically is at core. It tucks on other things, too, like negotiating alternate modes, USB data roles, power roles, role swaps, etc. But the core of the standard is just "here's a list of values, and here's a way to tell the source which value I want to use" + method of communicating + some legacy USB stuff and some simplified alternative methods for power sources without PD chips (resistor pull-ups on CC lines to negotiate between legacy/1.5A/3.0A).