Price Rate of Change
The Price ROC shows the difference between the current price and the price one or more periods in the past.
A 12-day Price ROC is most often used as an overbought/oversold indicator.
set PROC12= PROC(CLOSE, 12)
set BUY = PROC12 > 0 AND (REF(PROC12,1) < 0)
Evaluates to buy when the Price ROC recently shifted into positive territory.