you are writing ActionScript 3.0 code to be used in Flex, you can
place metadata in the code to embed external files in any published
SWF that includes the ActionScript code. Usually, these [Embed] metadata
declarations are used to embed image files, fonts, individual symbols,
or other SWF files into the SWF.
Remember that metadata is “data about data.” You add metadata
to ActionScript on the line immediately preceding the line of code
that the metadata applies to. The compiler then takes the metadata
into account when compiling the line of code that follows it.
For example, to embed an image called button_up.png that is stored
in the directory one level above the ActionScript file, you would
use the following ActionScript:
private var buttonUpImage:Class;
The [Embed] metadata tag tells the compiler
to embed the file named button_up.png in the SWF file and that the
file should be associated with the variable named buttonUpImage.
For more information about embedding assets with metadata in
Flex, see Embedding Assets in the Flex 3 Developer Guide at www.adobe.com/go/learn_flexresources_en.
If you use a feature that requires the Flex SDK, such as [Embed] metadata,
at compile time Flash Professional prompts you to
add the Flex.SWC file to the Library path of your FLA file. The
Flex.SWC file contains compiled classes needed to support Flex metadata.
Click Update Library Path in the dialog box to add Flex.SWC to the
Library path. You can also add the Flex.SWC file to the Library path
in the ActionScript publish settings later.