AFL for channels

Hello guys

I found the following AFL somewhere.. Can someone interpret it and tell me what exactly is it calculating for building a channel??


// Daily Bar Chart
//_SECTION_BEGIN("Daily Chart with Envelope");
//SetChartOptions(0,chartShowArrows|chartShowDates);
//Plot( EMA(C,13),"EMA(13)",colorRed,styleLine);
//PlotForeign(GetBaseIndex(),IndustryID(1),colorWhite,styleLine|styleLeftAxisScale);
// LookBkPd = 100 ;
// AvgPd = 22 ;
// ExternalBarPct = 15 ;
// ConvergePct = 2 ;
// Middle = EMA( C,AvgPd ) ;
// Rng = HHV( H,LookBkPd ) - LLV( L,LookBkPd ) ;
// X = Rng ;
// deltaX = X/2 ;
// do
// {
// Over = H > Middle + X ;
// Under = L < Middle - X ;
// OuterPct = 100*( Sum( Over, LookBkPd ) + Sum( Under, LookBkPd )
// )/LookBkPd ;
// OP = LastValue(OuterPct) ;
// X=X+sign( OP - ExternalBarPct )*deltaX ;
// deltaX = deltaX/2 ;
// }while ( abs( OP - ExternalBarPct ) > ConvergePct ) ;
// Plot( Middle, "MA", colorYellow, styleLine|styleNoTitle ) ;
// Plot( Middle+X, "MA", colorSkyblue, styleDashed|styleNoTitle ) ;
// Plot( Middle-X, "MA", colorSkyblue, styleDashed|styleNoTitle ) ;
//_N(Title = StrFormat("{{NAME}} - {{INTERVAL}} {{DATE}} Open %g, Hi %g, Lo %g,
Close %g (%.1f%%) {{VALUES}}", O, H, L, C, SelectedValue( ROC( C, 1 ) ) ));
//Plot( C, "Close", ParamColor("Color", colorCustom9 ), styleBar |
ParamStyle("Style") | GetPriceStyle() );
//_SECTION_END();