This indicator is the classical Bollinger Bands but built upon a ZeroLag exponential average and not with the original 20 periods SMA. The ZeroLag EMA is a variation of the EMA but add momentum short term weight of price to reduce lag.
Coded by request on the English forum.
// parameters
// period = 20
// dev = 2.0
lag = ROUND((period-1)/2)
data = (close + (close-close[lag]))
ZLEMA = exponentialaverage[period](data)
BolUp = ZLEMA+STD[period]*dev
BolDn = ZLEMA-STD[period]*dev
RETURN ZLEMA as "ZeroLag EMA", BolUp as "Bollinger Up ZLEMA", BolDn as "Bollinger Down ZLEMA"