This indicator shows an approximation of the effective bid-ask spread. It utilises an efficient estimator (Efficient Discrete Generalized Estimator or EDGE) which uses Open, High, Low and Close Prices as described in Ardia, David and Guidotti, Emanuele and Kroencke, Tim Alexander, "Efficient Estimation of Bid-Ask Spreads from Open, High, Low, and Close Prices"....
