[Embed(source="bitmap.png",scaleGridTop="10",scaleGridBottom="10",scaleGridLeft="10",scaleGridRight="10")]
private var png:Class;

Adobe说：

“You can use the [Embed] metadata tag to import
JPEG, GIF, PNG, SVG, SWF, TTF, and MP3 files.”

但我们可以通过下面的方法将XML也作为资源嵌入进SWF中

package example
{
import mx.core.ByteArrayAsset;

public final class Config
{
[Embed("config.xml", mimeType="application/octet-stream")]
private static const Config:Class;

public static function getConfig() : XML
{
var ba:ByteArrayAsset = ByteArrayAsset( new Config()) ;
var xml:XML = new XML( ba.readUTFBytes( ba.length ) );

return xml;
}
}
}

作者已经把此方法封装成了XMLAsset类，原文见这里

http://www.ericfeminella.com/blog/2008/07/27/xmlasset-api/