Flash CS3 Professional.
fl.scriptURI
Read-only property; a string that represents the path of the currently running JSFL script, expressed as a file:/// URI. If the script was called from fl.runScript(), this property represents the path of the immediate parent script. That is, it doesn’t traverse multiple calls to fl.runScript() to find the path of the original calling script.
The following example displays the path of the currently running JSFL script in the Output panel:
fl.trace(fl.scriptURI);