Bollinger Band Accurate Buy Sell Arrows - Amibroker AFL Code

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_SECTION_BEGIN("Bollinger Bands");
P = ParamField("Price field",-1);
Periods = Param("Periods", 15, 2, 100, 1 );
Width = Param("Width", 2, 0, 10, 0.05 );
Color = ParamColor("Color", colorCycle );
Style = ParamStyle("Style");
Plot( BBandTop( P, Periods, Width ), "BBTop" + _PARAM_VALUES(), colorWhite, style); 
Plot( BBandBot( P, Periods, Width ), "BBBot" + _PARAM_VALUES(), colorWhite, style ); 

Buy = Cross (Ref (C,-1), Ref (BBandBot(C,15), -1)) AND (Close > BBandBot(C,15)); 
PlotShapes(shapeUpArrow*Buy,colorLime,0,L,-10);
Sell = Cross ( Ref (BBandTop(C,15), -1),Ref (C,-1)) AND (BBandTop(C,15) > Close);
PlotShapes(shapeDownArrow*Sell,colorRed,0,H,-10);
Buy=ExRem(Buy,Sell); Sell=ExRem(Sell,Buy);

Filter = Buy OR Sell;
AddTextColumn(FullName(),"Name");
AddColumn( Buy, "BUY");
AddColumn( Sell, "SELL");
_SECTION_END();

_SECTION_BEGIN("Price");
SetChartOptions(0,chartShowArrows|chartShowDates);
_N(Title = StrFormat("{{NAME}} - {{INTERVAL}} {{DATE}} Open %g, Hi %g, Lo %g, Close %g (%.1f%%) Vol " +WriteVal( V, 1.0 ) +" {{VALUES}}", O, H, L, C, SelectedValue( ROC( C, 1 )) ));
Plot( C, "Close", ParamColor("Color", colorBlack ), styleNoTitle | ParamStyle("Style") | GetPriceStyle() ); 
if( ParamToggle("Tooltip shows", "All Values|Only Prices" ) )
{
 ToolTip=StrFormat("Open: %g\nHigh:  %g\nLow:   %g\nClose:  %g (%.1f%%)\nVolume: "+NumToStr( V, 1 ), O, H, L, C, SelectedValue( ROC( C, 1 )));
}
_SECTION_END();