Theory: Unlike the double smoothed stochastic itself (that was originally published here : Double Smoothed Stochastic), the "ratio" part of this version can be traced back to Walter Bressert - he uses it as an oscillator, but since that way of calculating (EMA(short)/EMA(...
from https://tradingrobots.net/double-smoothed-stochastic-of-ratio-indicator-for-metatrader-5/