A few good examples of trailing stops in Amibroker.
From the Traders Tips section of Technical Analysis of Stocks and Commodities magazine, May 2009:
Version(5.20); // requires v5.20
SetBarsRequired(sbrAll);

// get start date
Start = Cross( DateNum(), ParamDate(„Start date”, „2005-10-30” ) );
Started = Flip( Start, 0 );

StopMode = ParamToggle(„Stop Mode”, „Fixed|Chandelier” );
StopLevel = Param(„Fixed perc %”, 14, 0.1, 50, 0.1)/100;
StopATRFactor = Param(„Chandelier ATR multiple”, 4, 0.5, 10, 0.1 );
StopATRPeriod = Param(„Chandelier ATR period”, 14, 3, 50 );

// calculate support and resistance levels
if( StopMode == 0 ) // fixed percent trailing stop
{
sup = C * ( 1 - stoplevel );
res = C * ( 1 + stoplevel );
}
else // Chandelier ATR-based stop
{
sup = C - StopATRFactor * ATR( StopATRPeriod );
res = C + StopATRFactor * ATR( StopATRPeriod );
}

// calculate trailing stop line
trailARRAY = Null;
trailstop = 0;
for( i = 1; i < BarCount; i++ )
{
if( Started[ i ] == 0 ) continue;

if( C[ i ] > trailstop AND C[ i - 1 ] > trailstop )
trailstop = Max( trailstop, sup[ i ] );
else
if( C[ i ] < trailstop AND C[ i - 1 ] < trailstop )
trailstop = Min( trailstop, res[ i ] );
else
trailstop = IIf( C[ i ] > trailstop, sup[ i ], res[ i ] );

trailARRAY[ i ] = trailstop;
}

// generate buy/sell signals based on crossover with trail stop line
Buy = Start OR Cross( C, trailArray );
Sell = Cross( trailArray, C );

PlotShapes(Buy*shapeUpArrow,colorGreen,0,trailarray);
PlotShapes(Sell*shapeDownArrow,colorRed,0,trailarray);

Plot( Close,”Price”,colorBlack,styleBar);
Plot( trailARRAY,”trailing stop level”, colorRed );

—Tomasz Janeczko