Flash MX 2004.
fl.trace(message)
message A string that appears in the Output panel.
Nothing.
Method; sends a text string to the Output panel, terminated by a new line, and displays the Output panel if it is not already visible. This method is identical to outputPanel.trace() and works in the same way as the trace() statement in ActionScript. To send a blank line, use fl.trace("") or fl.trace("\n"). You can use the latter command inline, making \n a part of the message string.
The following example displays several lines of text in the Output panel:
fl.outputPanel.clear();
fl.trace("Hello World!!!");
var myPet = "cat";
fl.trace("\nI have a " + myPet);
fl.trace("");
fl.trace("I love my " + myPet);
fl.trace("Do you have a " + myPet +"?");