Ps is commonly referred to as Power Excess. It is part of the E-M Diagrams (Energy Maneuverability) All aircraft have them, but we punch the numbers before every tactical flight. Has various values that can all be cross referenced depending on what you want to get out of it. They are essentially multi-dimensional engineering charts. Each chart is for a given temperature, altitude and aircraft weight/configuration. (Specific for that aircraft.) You can get useful things such as Max AOB you can pull and still maintain level flight, radius of turn, max level airspeed, Max G, etc. All of those numbers can be determined for level flight, given rate of climb, given rate of descent, etc.
Even more sobering is that when reading them you can determine how fast you will fall out of the sky if you overbank in a given situation.