Percent Bands for Amibroker (AFL)

_SECTION_BEGIN("Percent Bands");
P = ParamField("Price field",-1);
Periods = Param("Periods", 15, 2, 300, 1 );
Width = Param("Width%", 2, 0, 10, 0.05 );
Color = ParamColor("Color", colorCycle );
Style = ParamStyle("Style");
CenterLine = MA( P, Periods );
Plot( (1 + Width * 0.01) * CenterLine, "%EnvTop" + _PARAM_VALUES(), Color, Style ); 
Plot( (1 - Width * 0.01) * CenterLine, "%EnvBot" + _PARAM_VALUES(), Color, Style ); 
_SECTION_END();