Percentage Price Oscillator: MACD rewritten as a percentage of the slow average, so the histogram of a 20 dollar stock and a 2000 dollar index can be read on the same axis.

Both the oscillator and its signal take a selectable EMA/SMA shape, and the signal is a MA of the PPO rather than of price, so it inherits the PPO's own warmup on top of its own: on defaults the oscillator prints from bar 25 and the signal and histogram from bar 33.