This is a very basic, but powerful script.
It gives you the ratio between the rate of change of the last x days and the average true range of the last y days.
---> ROC-ATR Ratio = ROC/ATR
Therefore, you can see how much the price has moved relative to the prices in the past.
This is important because (in my opinion) the basic ROC indicator is not very meaningful if you don't look at the average volatility of recent history.
For example, a ROC of 5% over the last 3 days might be very high for Forex but very small for some crypto.
Consequently, this indicator makes it possible to compare (and be used on) every instrument in every industry the same way.
Generally speaking, it makes more sense if the ATR length is larger than the ROC length.